TY  - JOUR
AU  - Belošević-Čavor, Jelena
AU  - Koteski, Vasil
AU  - Ivanovski, Valentin N.
AU  - Toprek, Dragan
AU  - Umićević, Ana
PY  - 2023
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/11641
AB  - In order to provide insight into the influence of co-doping with boron (B) and transition metals (TM = Pt, Ta, V) on the photoactivity of anatase TiO2 , the electronic, structural and optical characteristics of the mentioned co-doped systems were studied using density functional theory calculations and the modified Becke–Johnson exchange potential. For each transition metal two cases were considered, with B atom either replacing O atom (B-substitutional) or imbedding interstitially (B-interstitial) into TiO2 lattice. The calculations showed that the co-doping is more favorable for the B-interstitial systems than for the B-substitutional ones and under the O-rich conditions. For the B-substitutional cases a slight decrease of the band gap is observed. In contrast, the results obtained for the B-interstitial systems exhibited no band gap narrowing. However, in these systems, the occurrence of localized states within the band gap is noticed, which could improve visible light absorption through a two-step optical transition.
T2  - Physica B: Condensed Matter
T1  - Tailoring the photocatalytic properties of anatase TiO2 by B–TM (TM = Pt, Ta, V) co-doping
VL  - 670
SP  - 415358
DO  - 10.1016/j.physb.2023.415358
ER  - 

@article{
author = "Belošević-Čavor, Jelena and Koteski, Vasil and Ivanovski, Valentin N. and Toprek, Dragan and Umićević, Ana",
year = "2023",
abstract = "In order to provide insight into the influence of co-doping with boron (B) and transition metals (TM = Pt, Ta, V) on the photoactivity of anatase TiO2 , the electronic, structural and optical characteristics of the mentioned co-doped systems were studied using density functional theory calculations and the modified Becke–Johnson exchange potential. For each transition metal two cases were considered, with B atom either replacing O atom (B-substitutional) or imbedding interstitially (B-interstitial) into TiO2 lattice. The calculations showed that the co-doping is more favorable for the B-interstitial systems than for the B-substitutional ones and under the O-rich conditions. For the B-substitutional cases a slight decrease of the band gap is observed. In contrast, the results obtained for the B-interstitial systems exhibited no band gap narrowing. However, in these systems, the occurrence of localized states within the band gap is noticed, which could improve visible light absorption through a two-step optical transition.",
journal = "Physica B: Condensed Matter",
title = "Tailoring the photocatalytic properties of anatase TiO2 by B–TM (TM = Pt, Ta, V) co-doping",
volume = "670",
pages = "415358",
doi = "10.1016/j.physb.2023.415358"
}

Belošević-Čavor, J., Koteski, V., Ivanovski, V. N., Toprek, D.,& Umićević, A.. (2023). Tailoring the photocatalytic properties of anatase TiO2 by B–TM (TM = Pt, Ta, V) co-doping. in Physica B: Condensed Matter, 670, 415358.
https://doi.org/10.1016/j.physb.2023.415358

Belošević-Čavor J, Koteski V, Ivanovski VN, Toprek D, Umićević A. Tailoring the photocatalytic properties of anatase TiO2 by B–TM (TM = Pt, Ta, V) co-doping. in Physica B: Condensed Matter. 2023;670:415358.
doi:10.1016/j.physb.2023.415358 .

Belošević-Čavor, Jelena, Koteski, Vasil, Ivanovski, Valentin N., Toprek, Dragan, Umićević, Ana, "Tailoring the photocatalytic properties of anatase TiO2 by B–TM (TM = Pt, Ta, V) co-doping" in Physica B: Condensed Matter, 670 (2023):415358,
https://doi.org/10.1016/j.physb.2023.415358 . .

TY  - CONF
AU  - Umićević, Ana
AU  - Banerjee, D.
AU  - Dey, C. C.
AU  - Belošević-Čavor, Jelena
AU  - Koteski, Vasil
AU  - Ivanovski, Valentin
AU  - Toprek, Dragan
AU  - Kapidžić, Ana
AU  - Wasim Raja, Sk.
AU  - Dey Chaudhuri, S.
AU  - Blanuša, Jovan
PY  - 2023
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/12110
AB  - Laves phases (AB2) are alloys whose metal hydrides have been proposed to improve the energy density of Ni-MH batteries. In case of ZrV2-based battery materials, various amounts of different modifiers, such as Ti and Ni are used to improve their performance. The influence of Ni modifier in ZrV2 C15 Laves phase was investigated at atomic level by the 181TaPerturbed Angular Correlation (PAC) measurements of Zr(V0.33Ni0.67)2, Zr(V0.33Ni0.67)2.4 and Zr27V18Ni55 compounds. The dominant C15-type crystallographic structures were found in all samples by the X-ray diffraction, with the minority presence of other phases, mostly various oxides. The 181Ta-PAC preliminary results showed four different electric quadrupole interactions which give similar values for electric field gradients and non-zero asymmetry parameters in all investigated compounds.
C3  - HYPERFINE2023 : International Conference on Hyperfine Interactions and their Applications : Program & Abstracts
T1  - Perturbed angular correlation study of zirconium based C15 laves phases
SP  - 72
EP  - 72
UR  - https://hdl.handle.net/21.15107/rcub_vinar_12110
ER  - 

@conference{
author = "Umićević, Ana and Banerjee, D. and Dey, C. C. and Belošević-Čavor, Jelena and Koteski, Vasil and Ivanovski, Valentin and Toprek, Dragan and Kapidžić, Ana and Wasim Raja, Sk. and Dey Chaudhuri, S. and Blanuša, Jovan",
year = "2023",
abstract = "Laves phases (AB2) are alloys whose metal hydrides have been proposed to improve the energy density of Ni-MH batteries. In case of ZrV2-based battery materials, various amounts of different modifiers, such as Ti and Ni are used to improve their performance. The influence of Ni modifier in ZrV2 C15 Laves phase was investigated at atomic level by the 181TaPerturbed Angular Correlation (PAC) measurements of Zr(V0.33Ni0.67)2, Zr(V0.33Ni0.67)2.4 and Zr27V18Ni55 compounds. The dominant C15-type crystallographic structures were found in all samples by the X-ray diffraction, with the minority presence of other phases, mostly various oxides. The 181Ta-PAC preliminary results showed four different electric quadrupole interactions which give similar values for electric field gradients and non-zero asymmetry parameters in all investigated compounds.",
journal = "HYPERFINE2023 : International Conference on Hyperfine Interactions and their Applications : Program & Abstracts",
title = "Perturbed angular correlation study of zirconium based C15 laves phases",
pages = "72-72",
url = "https://hdl.handle.net/21.15107/rcub_vinar_12110"
}

Umićević, A., Banerjee, D., Dey, C. C., Belošević-Čavor, J., Koteski, V., Ivanovski, V., Toprek, D., Kapidžić, A., Wasim Raja, Sk., Dey Chaudhuri, S.,& Blanuša, J.. (2023). Perturbed angular correlation study of zirconium based C15 laves phases. in HYPERFINE2023 : International Conference on Hyperfine Interactions and their Applications : Program & Abstracts, 72-72.
https://hdl.handle.net/21.15107/rcub_vinar_12110

Umićević A, Banerjee D, Dey CC, Belošević-Čavor J, Koteski V, Ivanovski V, Toprek D, Kapidžić A, Wasim Raja S, Dey Chaudhuri S, Blanuša J. Perturbed angular correlation study of zirconium based C15 laves phases. in HYPERFINE2023 : International Conference on Hyperfine Interactions and their Applications : Program & Abstracts. 2023;:72-72.
https://hdl.handle.net/21.15107/rcub_vinar_12110 .

Umićević, Ana, Banerjee, D., Dey, C. C., Belošević-Čavor, Jelena, Koteski, Vasil, Ivanovski, Valentin, Toprek, Dragan, Kapidžić, Ana, Wasim Raja, Sk., Dey Chaudhuri, S., Blanuša, Jovan, "Perturbed angular correlation study of zirconium based C15 laves phases" in HYPERFINE2023 : International Conference on Hyperfine Interactions and their Applications : Program & Abstracts (2023):72-72,
https://hdl.handle.net/21.15107/rcub_vinar_12110 .

TY  - JOUR
AU  - Sewak, Ram
AU  - Dey, Chandi Charan
AU  - Toprek, Dragan
PY  - 2022
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/10638
AB  - Temperature dependent phase transformation behavior in cobalt from hexagonal close-packed (hcp) to face centered cubic (fcc) has been found to be contradictory to that reported earlier. It is found that hcp phase stabilizes at both low and high temperature ($$\sim $$873 K) while fcc phase is stabilized at $$\sim $$500 K. At 298 K, hcp Co has been found to be predominant ($$\sim $$70%) where hcp magnetic phase is $$\sim $$60%. At 973 K, hcp phase is again predominant ($$\sim $$73%), but it is mainly the non-magnetic phase ($$\sim $$67%). Contrary to present results, it was found earlier that fcc phase was stabilized at high temperature and hcp to fcc transformation occured at $$\sim $$700 K. Present results from perturbed angular correlation measurements, therefore, requires a new theoretical interpretation for Co phase transformation. From present measurements, hyperfine magnetic fields in Co at room temperature for the hcp and fcc phases have been found to be 18.7(6) and 12.8(3) T, much lower than earlier reported results. The hyperfine magnetic fields at $$^{181}$$Ta impurity atom have been calculated by density functional theory (DFT) employing the full potential (linearized) augmented plane wave method (FP-LAPW). Present calculated results for both hcp and fcc phases corroborate our experimental results.
T2  - Scientific Reports
T1  - Temperature induced phase transformation in Co
VL  - 12
IS  - 1
SP  - 10054
DO  - 10.1038/s41598-022-14302-x
ER  - 

@article{
author = "Sewak, Ram and Dey, Chandi Charan and Toprek, Dragan",
year = "2022",
abstract = "Temperature dependent phase transformation behavior in cobalt from hexagonal close-packed (hcp) to face centered cubic (fcc) has been found to be contradictory to that reported earlier. It is found that hcp phase stabilizes at both low and high temperature ($$\sim $$873 K) while fcc phase is stabilized at $$\sim $$500 K. At 298 K, hcp Co has been found to be predominant ($$\sim $$70%) where hcp magnetic phase is $$\sim $$60%. At 973 K, hcp phase is again predominant ($$\sim $$73%), but it is mainly the non-magnetic phase ($$\sim $$67%). Contrary to present results, it was found earlier that fcc phase was stabilized at high temperature and hcp to fcc transformation occured at $$\sim $$700 K. Present results from perturbed angular correlation measurements, therefore, requires a new theoretical interpretation for Co phase transformation. From present measurements, hyperfine magnetic fields in Co at room temperature for the hcp and fcc phases have been found to be 18.7(6) and 12.8(3) T, much lower than earlier reported results. The hyperfine magnetic fields at $$^{181}$$Ta impurity atom have been calculated by density functional theory (DFT) employing the full potential (linearized) augmented plane wave method (FP-LAPW). Present calculated results for both hcp and fcc phases corroborate our experimental results.",
journal = "Scientific Reports",
title = "Temperature induced phase transformation in Co",
volume = "12",
number = "1",
pages = "10054",
doi = "10.1038/s41598-022-14302-x"
}

Sewak, R., Dey, C. C.,& Toprek, D.. (2022). Temperature induced phase transformation in Co. in Scientific Reports, 12(1), 10054.
https://doi.org/10.1038/s41598-022-14302-x

Sewak R, Dey CC, Toprek D. Temperature induced phase transformation in Co. in Scientific Reports. 2022;12(1):10054.
doi:10.1038/s41598-022-14302-x .

Sewak, Ram, Dey, Chandi Charan, Toprek, Dragan, "Temperature induced phase transformation in Co" in Scientific Reports, 12, no. 1 (2022):10054,
https://doi.org/10.1038/s41598-022-14302-x . .

TY  - JOUR
AU  - Veljković, Filip M.
AU  - Radović, Ivana M.
AU  - Toprek, Dragan
AU  - Petrović, Đorđe
AU  - Stoiljković, Milovan
AU  - Mitić, Vojislav V.
AU  - Veličković, Suzana
PY  - 2021
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/10084
AB  - Due to the increased use of yttrium in agriculture and industry, there is a growing interest in the impact of yttrium on the environment and human health. Developing novel procedures to detect and quantify species of yttrium represents an important task. In this work, we apply laser desorption/ionization-mass spectrometry (LDI-MS) to detect cluster ions of the solution of yttrium(III) chloride (YCl3) at different pH values. The density functional theory (DFT) calculations were used to reveal the energetically most favored structures of the anions and cations chosen from the LDI-MS results. Examination of the positive and negative mode LDI mass spectra of YCl3 showed the presence of the heterogeneous mononuclear and polynuclear clusters, such as [YCl(OH) (H2O)3]++, [Y2(H2O)]++, [Y4H2(H2O)4]++, and [Y5O4H3]++ (at pH 2 and 5) and [Y2Cl2(H2O)2]−−, [Y2O5(HCl)(OH)]−−, and [Y3OH3(OH)2(H2O)]−− (at pH 2, 5, and 10). The variation in the pH solution of YCl3 slightly affects the LDI mass spectrum of these yttrium clusters. It has only been noticed that the [Y4H2(H2O)4]++ cluster ions were not detected at pH 10. These results can become a guide in the detection of yttrium chloride by LDI-MS in real samples in different fields (ecological, food, and human).
T2  - Modern Physics Letters B
T1  - Laser desorption/ionization time-of-flight mass spectrometry of yttrium(III) chloride
VL  - 35
IS  - 35
SP  - 2150454
DO  - 10.1142/S0217984921504546
ER  - 

@article{
author = "Veljković, Filip M. and Radović, Ivana M. and Toprek, Dragan and Petrović, Đorđe and Stoiljković, Milovan and Mitić, Vojislav V. and Veličković, Suzana",
year = "2021",
abstract = "Due to the increased use of yttrium in agriculture and industry, there is a growing interest in the impact of yttrium on the environment and human health. Developing novel procedures to detect and quantify species of yttrium represents an important task. In this work, we apply laser desorption/ionization-mass spectrometry (LDI-MS) to detect cluster ions of the solution of yttrium(III) chloride (YCl3) at different pH values. The density functional theory (DFT) calculations were used to reveal the energetically most favored structures of the anions and cations chosen from the LDI-MS results. Examination of the positive and negative mode LDI mass spectra of YCl3 showed the presence of the heterogeneous mononuclear and polynuclear clusters, such as [YCl(OH) (H2O)3]++, [Y2(H2O)]++, [Y4H2(H2O)4]++, and [Y5O4H3]++ (at pH 2 and 5) and [Y2Cl2(H2O)2]−−, [Y2O5(HCl)(OH)]−−, and [Y3OH3(OH)2(H2O)]−− (at pH 2, 5, and 10). The variation in the pH solution of YCl3 slightly affects the LDI mass spectrum of these yttrium clusters. It has only been noticed that the [Y4H2(H2O)4]++ cluster ions were not detected at pH 10. These results can become a guide in the detection of yttrium chloride by LDI-MS in real samples in different fields (ecological, food, and human).",
journal = "Modern Physics Letters B",
title = "Laser desorption/ionization time-of-flight mass spectrometry of yttrium(III) chloride",
volume = "35",
number = "35",
pages = "2150454",
doi = "10.1142/S0217984921504546"
}

Veljković, F. M., Radović, I. M., Toprek, D., Petrović, Đ., Stoiljković, M., Mitić, V. V.,& Veličković, S.. (2021). Laser desorption/ionization time-of-flight mass spectrometry of yttrium(III) chloride. in Modern Physics Letters B, 35(35), 2150454.
https://doi.org/10.1142/S0217984921504546

Veljković FM, Radović IM, Toprek D, Petrović Đ, Stoiljković M, Mitić VV, Veličković S. Laser desorption/ionization time-of-flight mass spectrometry of yttrium(III) chloride. in Modern Physics Letters B. 2021;35(35):2150454.
doi:10.1142/S0217984921504546 .

Veljković, Filip M., Radović, Ivana M., Toprek, Dragan, Petrović, Đorđe, Stoiljković, Milovan, Mitić, Vojislav V., Veličković, Suzana, "Laser desorption/ionization time-of-flight mass spectrometry of yttrium(III) chloride" in Modern Physics Letters B, 35, no. 35 (2021):2150454,
https://doi.org/10.1142/S0217984921504546 . .

TY  - JOUR
AU  - Toprek, Dragan
AU  - Koteski, Vasil J.
PY  - 2021
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/9139
AB  - In this paper we studied the effects of the concentration of W as a doped atom on the V lattice site on the electronic and optical properties of tetragonal zircon-type BiVO4 structure. The calculations were performed by the first-principles density functional theory WIEN2k code. The doping strategy was targeting V atoms substituted by W atoms using the same lattice parameters as pure BiVO4 structure. To avoid the self interaction of impurities, the supercell method was adopted ensuring a sufficient length between the impurities in all directions. For all considered concentrations, the optical properties in the visible light range of λ≥550nm are improved over the undoped BiVO4. © 2021 Elsevier B.V.
T2  - Materials Chemistry and Physics
T1  - Improving the photocatalytic activity of tetragonal BiVO4 with zircon-type structure through W doping; Ab initio calculations
VL  - 264
SP  - 124439
DO  - 10.1016/j.matchemphys.2021.124439
ER  - 

@article{
author = "Toprek, Dragan and Koteski, Vasil J.",
year = "2021",
abstract = "In this paper we studied the effects of the concentration of W as a doped atom on the V lattice site on the electronic and optical properties of tetragonal zircon-type BiVO4 structure. The calculations were performed by the first-principles density functional theory WIEN2k code. The doping strategy was targeting V atoms substituted by W atoms using the same lattice parameters as pure BiVO4 structure. To avoid the self interaction of impurities, the supercell method was adopted ensuring a sufficient length between the impurities in all directions. For all considered concentrations, the optical properties in the visible light range of λ≥550nm are improved over the undoped BiVO4. © 2021 Elsevier B.V.",
journal = "Materials Chemistry and Physics",
title = "Improving the photocatalytic activity of tetragonal BiVO4 with zircon-type structure through W doping; Ab initio calculations",
volume = "264",
pages = "124439",
doi = "10.1016/j.matchemphys.2021.124439"
}

Toprek, D.,& Koteski, V. J.. (2021). Improving the photocatalytic activity of tetragonal BiVO4 with zircon-type structure through W doping; Ab initio calculations. in Materials Chemistry and Physics, 264, 124439.
https://doi.org/10.1016/j.matchemphys.2021.124439

Toprek D, Koteski VJ. Improving the photocatalytic activity of tetragonal BiVO4 with zircon-type structure through W doping; Ab initio calculations. in Materials Chemistry and Physics. 2021;264:124439.
doi:10.1016/j.matchemphys.2021.124439 .

Toprek, Dragan, Koteski, Vasil J., "Improving the photocatalytic activity of tetragonal BiVO4 with zircon-type structure through W doping; Ab initio calculations" in Materials Chemistry and Physics, 264 (2021):124439,
https://doi.org/10.1016/j.matchemphys.2021.124439 . .

TY  - JOUR
AU  - Sewak, Ram
AU  - Dey, Chandi Charan
AU  - Toprek, Dragan
PY  - 2021
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/9704
AB  - Ferromagnetism in Hf6Co23 intermetallic alloy at room temperature has been confirmed from perturbed angular correlation measurements using 181Hf probe. The strength of hyperfine magnetic field at room temperature for this intermetallic compound has been found to be Bhf=2.5(2) T while the earlier report of hyperfine magnetic field in Hf6Co23 has discrepancy. The hyperfine magnetic field at Ta impurity site has also been calculated by density functional theory and the result is found to be Bhf=-4.964 T (at 0 K). This value is closer to the present experimental value measured at 298 K. The compound Hf6Co23 has been found to decompose reversibly to Hf2Co7 at 473 K. Ferromagnetism in this material has been found up to 423 K and its Curie temperature is, therefore, set as TC>423 K. From recent measurements by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, electron probe microanalysis and differential scanning calorimetry, Hf6Co23 was reported to be stable in a wide range of temperature and there was no phase existence of Hf2Co7 while the previous reported phase diagram showed a decomposition of Hf6Co23 to Hf2Co7 at a higher temperature. © 2021 Elsevier B.V.
T2  - Journal of Magnetism and Magnetic Materials
T1  - Ferromagnetism in intermetallic Hf6Co23 alloy
VL  - 534
SP  - 168042
DO  - 10.1016/j.jmmm.2021.168042
ER  - 

@article{
author = "Sewak, Ram and Dey, Chandi Charan and Toprek, Dragan",
year = "2021",
abstract = "Ferromagnetism in Hf6Co23 intermetallic alloy at room temperature has been confirmed from perturbed angular correlation measurements using 181Hf probe. The strength of hyperfine magnetic field at room temperature for this intermetallic compound has been found to be Bhf=2.5(2) T while the earlier report of hyperfine magnetic field in Hf6Co23 has discrepancy. The hyperfine magnetic field at Ta impurity site has also been calculated by density functional theory and the result is found to be Bhf=-4.964 T (at 0 K). This value is closer to the present experimental value measured at 298 K. The compound Hf6Co23 has been found to decompose reversibly to Hf2Co7 at 473 K. Ferromagnetism in this material has been found up to 423 K and its Curie temperature is, therefore, set as TC>423 K. From recent measurements by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, electron probe microanalysis and differential scanning calorimetry, Hf6Co23 was reported to be stable in a wide range of temperature and there was no phase existence of Hf2Co7 while the previous reported phase diagram showed a decomposition of Hf6Co23 to Hf2Co7 at a higher temperature. © 2021 Elsevier B.V.",
journal = "Journal of Magnetism and Magnetic Materials",
title = "Ferromagnetism in intermetallic Hf6Co23 alloy",
volume = "534",
pages = "168042",
doi = "10.1016/j.jmmm.2021.168042"
}

Sewak, R., Dey, C. C.,& Toprek, D.. (2021). Ferromagnetism in intermetallic Hf6Co23 alloy. in Journal of Magnetism and Magnetic Materials, 534, 168042.
https://doi.org/10.1016/j.jmmm.2021.168042

Sewak R, Dey CC, Toprek D. Ferromagnetism in intermetallic Hf6Co23 alloy. in Journal of Magnetism and Magnetic Materials. 2021;534:168042.
doi:10.1016/j.jmmm.2021.168042 .

Sewak, Ram, Dey, Chandi Charan, Toprek, Dragan, "Ferromagnetism in intermetallic Hf6Co23 alloy" in Journal of Magnetism and Magnetic Materials, 534 (2021):168042,
https://doi.org/10.1016/j.jmmm.2021.168042 . .

TY  - JOUR
AU  - Banerjee, Debashis
AU  - Sewak, Ram
AU  - Dey, Chandi Charan
AU  - Toprek, Dragan
AU  - Pujari, Pradeep Kumar
PY  - 2021
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/9757
AB  - In pure HfO2, only P21/c monoclinic phase was known to exist from previous investigations and there is no report of orthorhombic phase in pure bulk HfO2 at ambient temperature and pressure. Present atomic scale measurements by perturbed angular correlation (PAC) spectroscopy, report two orthorhombic phases in pure bulk HfO2 at room temperature along with the most commonly observed monoclinic phase (similar to 80%). By comparing with the calculated results of density functional theory using full potential (linearized) augmented plane wave method (FP-LAPW), these two orthorhombic phases have been attributed to structures with space group Pbca and Pca2(1). The structures with space group Pca2(1) and Pmn2(1) are non-centrosymmetric and were found to be responsible for ferroelectricity in doped thin film HfO2. At room temperature, the site percentages for the Pca2(1) and Pbca have been found to be similar to 6% and similar to 10%, respectively. At high temperatures of 973 and 1073 K, the Pca2(1) phase was not found but, the Pbca orthorhombic phase was found to be present in the whole temperature range from 298 to 1073 K. The third orthorhombic phase Pmn2(1) was not observed in bulk HfO2. Interestingly, In Gd doped (similar to 5 at%) HfO2, these two orthorhombic phases enhance more than the monoclinic phase. In Gd doped oxide, the P21/c monoclinic phase reduces to similar to 24% while the site percentages for the two orthorhombic phases have been found to be similar to 54% (Pbca) and similar to 17% (Pca2(1)).
T2  - Materials Today Communications
T1  - Orthorhombic phases in bulk pure HfO2: Experimental observation from perturbed angular correlation spectroscopy
VL  - 26
SP  - 101827
DO  - 10.1016/j.mtcomm.2020.101827
ER  - 

@article{
author = "Banerjee, Debashis and Sewak, Ram and Dey, Chandi Charan and Toprek, Dragan and Pujari, Pradeep Kumar",
year = "2021",
abstract = "In pure HfO2, only P21/c monoclinic phase was known to exist from previous investigations and there is no report of orthorhombic phase in pure bulk HfO2 at ambient temperature and pressure. Present atomic scale measurements by perturbed angular correlation (PAC) spectroscopy, report two orthorhombic phases in pure bulk HfO2 at room temperature along with the most commonly observed monoclinic phase (similar to 80%). By comparing with the calculated results of density functional theory using full potential (linearized) augmented plane wave method (FP-LAPW), these two orthorhombic phases have been attributed to structures with space group Pbca and Pca2(1). The structures with space group Pca2(1) and Pmn2(1) are non-centrosymmetric and were found to be responsible for ferroelectricity in doped thin film HfO2. At room temperature, the site percentages for the Pca2(1) and Pbca have been found to be similar to 6% and similar to 10%, respectively. At high temperatures of 973 and 1073 K, the Pca2(1) phase was not found but, the Pbca orthorhombic phase was found to be present in the whole temperature range from 298 to 1073 K. The third orthorhombic phase Pmn2(1) was not observed in bulk HfO2. Interestingly, In Gd doped (similar to 5 at%) HfO2, these two orthorhombic phases enhance more than the monoclinic phase. In Gd doped oxide, the P21/c monoclinic phase reduces to similar to 24% while the site percentages for the two orthorhombic phases have been found to be similar to 54% (Pbca) and similar to 17% (Pca2(1)).",
journal = "Materials Today Communications",
title = "Orthorhombic phases in bulk pure HfO2: Experimental observation from perturbed angular correlation spectroscopy",
volume = "26",
pages = "101827",
doi = "10.1016/j.mtcomm.2020.101827"
}

Banerjee, D., Sewak, R., Dey, C. C., Toprek, D.,& Pujari, P. K.. (2021). Orthorhombic phases in bulk pure HfO2: Experimental observation from perturbed angular correlation spectroscopy. in Materials Today Communications, 26, 101827.
https://doi.org/10.1016/j.mtcomm.2020.101827

Banerjee D, Sewak R, Dey CC, Toprek D, Pujari PK. Orthorhombic phases in bulk pure HfO2: Experimental observation from perturbed angular correlation spectroscopy. in Materials Today Communications. 2021;26:101827.
doi:10.1016/j.mtcomm.2020.101827 .

Banerjee, Debashis, Sewak, Ram, Dey, Chandi Charan, Toprek, Dragan, Pujari, Pradeep Kumar, "Orthorhombic phases in bulk pure HfO2: Experimental observation from perturbed angular correlation spectroscopy" in Materials Today Communications, 26 (2021):101827,
https://doi.org/10.1016/j.mtcomm.2020.101827 . .

TY  - JOUR
AU  - Banerjee, Debashis
AU  - Dey, Chandi Charan
AU  - Sewak, Ram
AU  - Thakare, Sanjay V.
AU  - Toprek, Dragan
PY  - 2021
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/10034
AB  - The recently observed ferroelectricity in thin films of pure and doped Hafnium oxide (HfO2) has initiated a sustaining effort to stabilize its ferroelectric phase which is the polar orthorhombic (o) phase with space group Pca21. This polar o-phase of the oxide does not appear in its phase transition sequence and is also not thought to be stabilized in bulk oxide. Here, we report the stabilization of three o-phases of this oxide in bulk with space groups Pbca, Pca21 and Pbcm in presence of Yttrium (Y) dopant. For inducing o-phase, 10 at% of Y-dopant has been used and temperature mediated phase transformation from monoclinic (m) to o-phase has been observed. The third o-phase with space group Pbcm could be stabilized for the first time in bulk oxide by Y-dopant. All the o-phases in presence of m-phase could be identified by Time Differential Perturbed γ-γ Angular Correlation (TDPAC) Spectroscopy. The TDPAC parameters assigned to Pbcm phase confirm the theoretical modelization for the phase performed by Wien2K calculation based on Density Functional Theory (DFT). The present work reports the possibility of stabilizing different o-phases including polar one and shows the widening of scope of this oxide for future ferroelectric applications.
T2  - Hyperfine Interactions
T1  - Orthorhombic structure stabilazation in bulk HfO2 by yttrium doping
VL  - 242
IS  - 1
SP  - 31
DO  - 10.1007/s10751-021-01765-z
ER  - 

@article{
author = "Banerjee, Debashis and Dey, Chandi Charan and Sewak, Ram and Thakare, Sanjay V. and Toprek, Dragan",
year = "2021",
abstract = "The recently observed ferroelectricity in thin films of pure and doped Hafnium oxide (HfO2) has initiated a sustaining effort to stabilize its ferroelectric phase which is the polar orthorhombic (o) phase with space group Pca21. This polar o-phase of the oxide does not appear in its phase transition sequence and is also not thought to be stabilized in bulk oxide. Here, we report the stabilization of three o-phases of this oxide in bulk with space groups Pbca, Pca21 and Pbcm in presence of Yttrium (Y) dopant. For inducing o-phase, 10 at% of Y-dopant has been used and temperature mediated phase transformation from monoclinic (m) to o-phase has been observed. The third o-phase with space group Pbcm could be stabilized for the first time in bulk oxide by Y-dopant. All the o-phases in presence of m-phase could be identified by Time Differential Perturbed γ-γ Angular Correlation (TDPAC) Spectroscopy. The TDPAC parameters assigned to Pbcm phase confirm the theoretical modelization for the phase performed by Wien2K calculation based on Density Functional Theory (DFT). The present work reports the possibility of stabilizing different o-phases including polar one and shows the widening of scope of this oxide for future ferroelectric applications.",
journal = "Hyperfine Interactions",
title = "Orthorhombic structure stabilazation in bulk HfO2 by yttrium doping",
volume = "242",
number = "1",
pages = "31",
doi = "10.1007/s10751-021-01765-z"
}

Banerjee, D., Dey, C. C., Sewak, R., Thakare, S. V.,& Toprek, D.. (2021). Orthorhombic structure stabilazation in bulk HfO2 by yttrium doping. in Hyperfine Interactions, 242(1), 31.
https://doi.org/10.1007/s10751-021-01765-z

Banerjee D, Dey CC, Sewak R, Thakare SV, Toprek D. Orthorhombic structure stabilazation in bulk HfO2 by yttrium doping. in Hyperfine Interactions. 2021;242(1):31.
doi:10.1007/s10751-021-01765-z .

Banerjee, Debashis, Dey, Chandi Charan, Sewak, Ram, Thakare, Sanjay V., Toprek, Dragan, "Orthorhombic structure stabilazation in bulk HfO2 by yttrium doping" in Hyperfine Interactions, 242, no. 1 (2021):31,
https://doi.org/10.1007/s10751-021-01765-z . .

TY  - JOUR
AU  - Koteski, Vasil J.
AU  - Belošević-Čavor, Jelena
AU  - Ivanovski, Valentin N.
AU  - Umićević, Ana
AU  - Toprek, Dragan
PY  - 2020
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/8889
AB  - Substitutionally doped Bi2W1-xMxO6 (M = Mo, Cr, Fe, Zn; x = 0.125, 0,25, 0.5) is investigated using the density functional theory (DFT). For all the investigated transition metal dopants, the optical properties in the visible light range are improved over the undoped Bi2WO6. Irrespective of concentration, the lattice relaxation around the dopants is constrained to the first coordination shell. Mo, Fe, and Cr introduce localized defect states in the band gap, contributing to band gap narrowing. The localized states are hybridized between the impurity d–bands and host W 5d–and O 2p–states. Zn facilitates the reduction of the band gap by inducing a shift of the states near the top of the valence band toward higher energies. Our results suggest that Zn doping on the W lattice site may improve the photocatalytic properties of Bi2WO6 more than the other dopants.
T2  - Applied Surface Science
T1  - Ab initio calculations of the optical and electronic properties of Bi2WO6 doped with Mo, Cr, Fe, and Zn on the W–lattice site
VL  - 515
SP  - 146036
DO  - 10.1016/j.apsusc.2020.146036
ER  - 

@article{
author = "Koteski, Vasil J. and Belošević-Čavor, Jelena and Ivanovski, Valentin N. and Umićević, Ana and Toprek, Dragan",
year = "2020",
abstract = "Substitutionally doped Bi2W1-xMxO6 (M = Mo, Cr, Fe, Zn; x = 0.125, 0,25, 0.5) is investigated using the density functional theory (DFT). For all the investigated transition metal dopants, the optical properties in the visible light range are improved over the undoped Bi2WO6. Irrespective of concentration, the lattice relaxation around the dopants is constrained to the first coordination shell. Mo, Fe, and Cr introduce localized defect states in the band gap, contributing to band gap narrowing. The localized states are hybridized between the impurity d–bands and host W 5d–and O 2p–states. Zn facilitates the reduction of the band gap by inducing a shift of the states near the top of the valence band toward higher energies. Our results suggest that Zn doping on the W lattice site may improve the photocatalytic properties of Bi2WO6 more than the other dopants.",
journal = "Applied Surface Science",
title = "Ab initio calculations of the optical and electronic properties of Bi2WO6 doped with Mo, Cr, Fe, and Zn on the W–lattice site",
volume = "515",
pages = "146036",
doi = "10.1016/j.apsusc.2020.146036"
}

Koteski, V. J., Belošević-Čavor, J., Ivanovski, V. N., Umićević, A.,& Toprek, D.. (2020). Ab initio calculations of the optical and electronic properties of Bi2WO6 doped with Mo, Cr, Fe, and Zn on the W–lattice site. in Applied Surface Science, 515, 146036.
https://doi.org/10.1016/j.apsusc.2020.146036

Koteski VJ, Belošević-Čavor J, Ivanovski VN, Umićević A, Toprek D. Ab initio calculations of the optical and electronic properties of Bi2WO6 doped with Mo, Cr, Fe, and Zn on the W–lattice site. in Applied Surface Science. 2020;515:146036.
doi:10.1016/j.apsusc.2020.146036 .

Koteski, Vasil J., Belošević-Čavor, Jelena, Ivanovski, Valentin N., Umićević, Ana, Toprek, Dragan, "Ab initio calculations of the optical and electronic properties of Bi2WO6 doped with Mo, Cr, Fe, and Zn on the W–lattice site" in Applied Surface Science, 515 (2020):146036,
https://doi.org/10.1016/j.apsusc.2020.146036 . .

TY  - JOUR
AU  - Dey, Sandhya K.
AU  - Dey, Chandi Charan
AU  - Saha, Saibal
AU  - Bhattacharjee, G.
AU  - Belošević-Čavor, Jelena
AU  - Toprek, Dragan
PY  - 2019
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/7937
AB  - Crystalline phases formed in stoichiometric Zr9Ni11 and Hf9Ni11 have been studied by perturbed angular correlation (PAC) spectroscopy, XRD and TEM/SAED measurements. In Zr9Ni11, the phases Zr9Ni11 (∼89%) and Zr8Ni21 (∼11%) have been found at room temperature from PAC measurements. At 773 K, Zr9Ni11 partially decomposes to Zr7Ni10 and at 973 K, it is completely decomposed to ZrNi and Zr7Ni10. In Hf9Ni11, a predominant phase (∼81%) due to HfNi is found at room temperature while the phase Hf9Ni11 is produced as a minor phase (∼19%). No compositional phase change at higher temperature is found in Hf9Ni11. Phase components found from XRD and TEM/SAED measurements are similar to those observed from PAC measurements. Electric field gradients in Zr9Ni11 and Hf9Ni11 have been calculated by density functional theory (DFT) using all electron full potential (linearized) augmented plane wave plus local orbitals [FP-(L)APW+lo] method in order to assign the phase components.
T2  - Journal of Solid State Chemistry
T1  - Crystalline phases in Zr9Ni11 and Hf9Ni11 intermetallics; Investigations by perturbed angular correlation spectroscopy and ab initio calculations
VL  - 269
SP  - 476
EP  - 485
DO  - 10.1016/j.jssc.2018.10.001
ER  - 

@article{
author = "Dey, Sandhya K. and Dey, Chandi Charan and Saha, Saibal and Bhattacharjee, G. and Belošević-Čavor, Jelena and Toprek, Dragan",
year = "2019",
abstract = "Crystalline phases formed in stoichiometric Zr9Ni11 and Hf9Ni11 have been studied by perturbed angular correlation (PAC) spectroscopy, XRD and TEM/SAED measurements. In Zr9Ni11, the phases Zr9Ni11 (∼89%) and Zr8Ni21 (∼11%) have been found at room temperature from PAC measurements. At 773 K, Zr9Ni11 partially decomposes to Zr7Ni10 and at 973 K, it is completely decomposed to ZrNi and Zr7Ni10. In Hf9Ni11, a predominant phase (∼81%) due to HfNi is found at room temperature while the phase Hf9Ni11 is produced as a minor phase (∼19%). No compositional phase change at higher temperature is found in Hf9Ni11. Phase components found from XRD and TEM/SAED measurements are similar to those observed from PAC measurements. Electric field gradients in Zr9Ni11 and Hf9Ni11 have been calculated by density functional theory (DFT) using all electron full potential (linearized) augmented plane wave plus local orbitals [FP-(L)APW+lo] method in order to assign the phase components.",
journal = "Journal of Solid State Chemistry",
title = "Crystalline phases in Zr9Ni11 and Hf9Ni11 intermetallics; Investigations by perturbed angular correlation spectroscopy and ab initio calculations",
volume = "269",
pages = "476-485",
doi = "10.1016/j.jssc.2018.10.001"
}

Dey, S. K., Dey, C. C., Saha, S., Bhattacharjee, G., Belošević-Čavor, J.,& Toprek, D.. (2019). Crystalline phases in Zr9Ni11 and Hf9Ni11 intermetallics; Investigations by perturbed angular correlation spectroscopy and ab initio calculations. in Journal of Solid State Chemistry, 269, 476-485.
https://doi.org/10.1016/j.jssc.2018.10.001

Dey SK, Dey CC, Saha S, Bhattacharjee G, Belošević-Čavor J, Toprek D. Crystalline phases in Zr9Ni11 and Hf9Ni11 intermetallics; Investigations by perturbed angular correlation spectroscopy and ab initio calculations. in Journal of Solid State Chemistry. 2019;269:476-485.
doi:10.1016/j.jssc.2018.10.001 .

Dey, Sandhya K., Dey, Chandi Charan, Saha, Saibal, Bhattacharjee, G., Belošević-Čavor, Jelena, Toprek, Dragan, "Crystalline phases in Zr9Ni11 and Hf9Ni11 intermetallics; Investigations by perturbed angular correlation spectroscopy and ab initio calculations" in Journal of Solid State Chemistry, 269 (2019):476-485,
https://doi.org/10.1016/j.jssc.2018.10.001 . .

TY  - JOUR
AU  - Dey, Sandhya K.
AU  - Dey, Chandi Charan
AU  - Saha, Saibal
AU  - Bhattacharjee, G.
AU  - Belošević-Čavor, Jelena
AU  - Toprek, Dragan
PY  - 2019
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/7939
UR  - https://arxiv.org/pdf/1712.04258.pdf
AB  - Crystalline phases formed in stoichiometric Zr9Ni11 and Hf9Ni11 have been studied by perturbed angular correlation (PAC) spectroscopy, XRD and TEM/SAED measurements. In Zr9Ni11, the phases Zr9Ni11 (∼89%) and Zr8Ni21 (∼11%) have been found at room temperature from PAC measurements. At 773 K, Zr9Ni11 partially decomposes to Zr7Ni10 and at 973 K, it is completely decomposed to ZrNi and Zr7Ni10. In Hf9Ni11, a predominant phase (∼81%) due to HfNi is found at room temperature while the phase Hf9Ni11 is produced as a minor phase (∼19%). No compositional phase change at higher temperature is found in Hf9Ni11. Phase components found from XRD and TEM/SAED measurements are similar to those observed from PAC measurements. Electric field gradients in Zr9Ni11 and Hf9Ni11 have been calculated by density functional theory (DFT) using all electron full potential (linearized) augmented plane wave plus local orbitals [FP-(L)APW+lo] method in order to assign the phase components.
T2  - Journal of Solid State Chemistry
T1  - Crystalline phases in Zr9Ni11 and Hf9Ni11 intermetallics; Investigations by perturbed angular correlation spectroscopy and ab initio calculations
VL  - 269
SP  - 476
EP  - 485
DO  - 10.1016/j.jssc.2018.10.001
ER  - 

@article{
author = "Dey, Sandhya K. and Dey, Chandi Charan and Saha, Saibal and Bhattacharjee, G. and Belošević-Čavor, Jelena and Toprek, Dragan",
year = "2019",
abstract = "Crystalline phases formed in stoichiometric Zr9Ni11 and Hf9Ni11 have been studied by perturbed angular correlation (PAC) spectroscopy, XRD and TEM/SAED measurements. In Zr9Ni11, the phases Zr9Ni11 (∼89%) and Zr8Ni21 (∼11%) have been found at room temperature from PAC measurements. At 773 K, Zr9Ni11 partially decomposes to Zr7Ni10 and at 973 K, it is completely decomposed to ZrNi and Zr7Ni10. In Hf9Ni11, a predominant phase (∼81%) due to HfNi is found at room temperature while the phase Hf9Ni11 is produced as a minor phase (∼19%). No compositional phase change at higher temperature is found in Hf9Ni11. Phase components found from XRD and TEM/SAED measurements are similar to those observed from PAC measurements. Electric field gradients in Zr9Ni11 and Hf9Ni11 have been calculated by density functional theory (DFT) using all electron full potential (linearized) augmented plane wave plus local orbitals [FP-(L)APW+lo] method in order to assign the phase components.",
journal = "Journal of Solid State Chemistry",
title = "Crystalline phases in Zr9Ni11 and Hf9Ni11 intermetallics; Investigations by perturbed angular correlation spectroscopy and ab initio calculations",
volume = "269",
pages = "476-485",
doi = "10.1016/j.jssc.2018.10.001"
}

Dey, S. K., Dey, C. C., Saha, S., Bhattacharjee, G., Belošević-Čavor, J.,& Toprek, D.. (2019). Crystalline phases in Zr9Ni11 and Hf9Ni11 intermetallics; Investigations by perturbed angular correlation spectroscopy and ab initio calculations. in Journal of Solid State Chemistry, 269, 476-485.
https://doi.org/10.1016/j.jssc.2018.10.001

Dey SK, Dey CC, Saha S, Bhattacharjee G, Belošević-Čavor J, Toprek D. Crystalline phases in Zr9Ni11 and Hf9Ni11 intermetallics; Investigations by perturbed angular correlation spectroscopy and ab initio calculations. in Journal of Solid State Chemistry. 2019;269:476-485.
doi:10.1016/j.jssc.2018.10.001 .

Dey, Sandhya K., Dey, Chandi Charan, Saha, Saibal, Bhattacharjee, G., Belošević-Čavor, Jelena, Toprek, Dragan, "Crystalline phases in Zr9Ni11 and Hf9Ni11 intermetallics; Investigations by perturbed angular correlation spectroscopy and ab initio calculations" in Journal of Solid State Chemistry, 269 (2019):476-485,
https://doi.org/10.1016/j.jssc.2018.10.001 . .

TY  - JOUR
AU  - Dey, Sourav Kumar
AU  - Dey, Chandi Charan
AU  - Saha, Satyajit
AU  - Banerjee, Debashis
AU  - Toprek, Dragan
PY  - 2019
UR  - http://link.springer.com/10.1007/s10751-019-1568-9
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/8104
AB  - Intermetallic compound Zr 7 Ni 10 has been studied by perturbed angular correlation (PAC) spectroscopy to determine the electric field gradient and site occupation of Hf dopant in the compound. A mixture of phase components were found in this sample. The component with V zz = 6.6(1)× 10 21 V/m 2 and η = 0.71(1) at room temperature has been assigned to Zr 7 Ni 10 phase. In this sample, Zr 2 Ni 7 and Zr 8 Ni 21 phases were also found to be present along with Zr 7 Ni 10 . No phase transition is observed in the temperature range 77-1073 K in this sample. The electric field gradient (V zz ) for Zr 7 Ni 10 phase was found to decrease linearly with temperature. The phase components in Zr 7 Ni 10 have been determined also from X-ray powder diffraction (XRD) measurement. Theoretical calculations of EFG have been performed in Ta-doped Zr 7 Ni 10 using all electron full potential (linearized) augmented plane wave [FP-(L)APW] method, within the framework of the density functional theory (DFT) to compare the results with the values obtained from PAC measurements and to know the site preference of 181 Ta probe in the host matrix.
T2  - Hyperfine Interactions
T1  - Local structure study of 181Hf dopants in Zr7Ni10 by perturbed angular correlation spectroscopy and first principles calculations
VL  - 240
IS  - 1
SP  - 25
DO  - 10.1007/s10751-019-1568-9
ER  - 

@article{
author = "Dey, Sourav Kumar and Dey, Chandi Charan and Saha, Satyajit and Banerjee, Debashis and Toprek, Dragan",
year = "2019",
abstract = "Intermetallic compound Zr 7 Ni 10 has been studied by perturbed angular correlation (PAC) spectroscopy to determine the electric field gradient and site occupation of Hf dopant in the compound. A mixture of phase components were found in this sample. The component with V zz = 6.6(1)× 10 21 V/m 2 and η = 0.71(1) at room temperature has been assigned to Zr 7 Ni 10 phase. In this sample, Zr 2 Ni 7 and Zr 8 Ni 21 phases were also found to be present along with Zr 7 Ni 10 . No phase transition is observed in the temperature range 77-1073 K in this sample. The electric field gradient (V zz ) for Zr 7 Ni 10 phase was found to decrease linearly with temperature. The phase components in Zr 7 Ni 10 have been determined also from X-ray powder diffraction (XRD) measurement. Theoretical calculations of EFG have been performed in Ta-doped Zr 7 Ni 10 using all electron full potential (linearized) augmented plane wave [FP-(L)APW] method, within the framework of the density functional theory (DFT) to compare the results with the values obtained from PAC measurements and to know the site preference of 181 Ta probe in the host matrix.",
journal = "Hyperfine Interactions",
title = "Local structure study of 181Hf dopants in Zr7Ni10 by perturbed angular correlation spectroscopy and first principles calculations",
volume = "240",
number = "1",
pages = "25",
doi = "10.1007/s10751-019-1568-9"
}

Dey, S. K., Dey, C. C., Saha, S., Banerjee, D.,& Toprek, D.. (2019). Local structure study of 181Hf dopants in Zr7Ni10 by perturbed angular correlation spectroscopy and first principles calculations. in Hyperfine Interactions, 240(1), 25.
https://doi.org/10.1007/s10751-019-1568-9

Dey SK, Dey CC, Saha S, Banerjee D, Toprek D. Local structure study of 181Hf dopants in Zr7Ni10 by perturbed angular correlation spectroscopy and first principles calculations. in Hyperfine Interactions. 2019;240(1):25.
doi:10.1007/s10751-019-1568-9 .

Dey, Sourav Kumar, Dey, Chandi Charan, Saha, Satyajit, Banerjee, Debashis, Toprek, Dragan, "Local structure study of 181Hf dopants in Zr7Ni10 by perturbed angular correlation spectroscopy and first principles calculations" in Hyperfine Interactions, 240, no. 1 (2019):25,
https://doi.org/10.1007/s10751-019-1568-9 . .

TY  - JOUR
AU  - Fontbonne, C.
AU  - Ujić, Predrag
AU  - de Oliveira Santos, F.
AU  - Flechard, Xavier
AU  - Rotaru, Florin
AU  - Achouri, Lynda N.
AU  - Girard Alcindor, V.
AU  - Bastin, Beyhan
AU  - Boulay, Francois
AU  - Briand, J. B.
AU  - Sanchez-Benitez, Angel Miguel
AU  - Bouzomita, H.
AU  - Borcea, Catalin
AU  - Borcea, Ruxandra
AU  - Blank, Bertram B.
AU  - Carniol, Benjamin
AU  - Čeliković, Igor T.
AU  - Delahaye, Pierre
AU  - Delaunay, F.
AU  - Etasse, David
AU  - Fremont, Georges
AU  - de France, Gilles
AU  - Fontbonne, Jean Marc
AU  - Grinyer, G. F.
AU  - Harang, J.
AU  - Hommet, Jean
AU  - Jevremović, Aleksandar M.
AU  - Lewitowicz, Marek
AU  - Martel, Ismael
AU  - Mrazek, Jaromir
AU  - Parlog, Marian
AU  - Poincheval, J.
AU  - Ramos, Diego
AU  - Spitaels, C.
AU  - Stanoiu, Mihai
AU  - Thomas, Jean-Charles
AU  - Toprek, Dragan
PY  - 2017
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1864
AB  - The half-life of Ne-19 was measured using a real-time digital multiparametric acquisition system, providing an accurate time stamp and relevant information on the detector signals for each decay event. An exhaustive offline analysis of the data gave unique access to experimental effects potentially biasing the measurement. After establishing the influence factors impacting the measurement such as after-pulses, pile-up, gain, and baseline fluctuations, their effects were accurately estimated and the event selection optimized. The resulting half-life, 17.2569 +/- 0.0019((stat)) +/- 0.0009((syst)) s, is the most precise up to now for Ne-19. It is found to be in agreement with two recent precise measurements and not consistent with the most recent one [L.J. Broussard et al., Phys. Rev. Lett. 112, 212301 (2014)] by 3.0 standard deviations. The full potential of the technique for nuclei with half-lives of a few seconds is discussed.
T2  - Physical Review C
T1  - High precision measurement of the Ne-19 beta-decay half-life using real-time digital acquisition
VL  - 96
IS  - 6
DO  - 10.1103/PhysRevC.96.065501
ER  - 

@article{
author = "Fontbonne, C. and Ujić, Predrag and de Oliveira Santos, F. and Flechard, Xavier and Rotaru, Florin and Achouri, Lynda N. and Girard Alcindor, V. and Bastin, Beyhan and Boulay, Francois and Briand, J. B. and Sanchez-Benitez, Angel Miguel and Bouzomita, H. and Borcea, Catalin and Borcea, Ruxandra and Blank, Bertram B. and Carniol, Benjamin and Čeliković, Igor T. and Delahaye, Pierre and Delaunay, F. and Etasse, David and Fremont, Georges and de France, Gilles and Fontbonne, Jean Marc and Grinyer, G. F. and Harang, J. and Hommet, Jean and Jevremović, Aleksandar M. and Lewitowicz, Marek and Martel, Ismael and Mrazek, Jaromir and Parlog, Marian and Poincheval, J. and Ramos, Diego and Spitaels, C. and Stanoiu, Mihai and Thomas, Jean-Charles and Toprek, Dragan",
year = "2017",
abstract = "The half-life of Ne-19 was measured using a real-time digital multiparametric acquisition system, providing an accurate time stamp and relevant information on the detector signals for each decay event. An exhaustive offline analysis of the data gave unique access to experimental effects potentially biasing the measurement. After establishing the influence factors impacting the measurement such as after-pulses, pile-up, gain, and baseline fluctuations, their effects were accurately estimated and the event selection optimized. The resulting half-life, 17.2569 +/- 0.0019((stat)) +/- 0.0009((syst)) s, is the most precise up to now for Ne-19. It is found to be in agreement with two recent precise measurements and not consistent with the most recent one [L.J. Broussard et al., Phys. Rev. Lett. 112, 212301 (2014)] by 3.0 standard deviations. The full potential of the technique for nuclei with half-lives of a few seconds is discussed.",
journal = "Physical Review C",
title = "High precision measurement of the Ne-19 beta-decay half-life using real-time digital acquisition",
volume = "96",
number = "6",
doi = "10.1103/PhysRevC.96.065501"
}

Fontbonne, C., Ujić, P., de Oliveira Santos, F., Flechard, X., Rotaru, F., Achouri, L. N., Girard Alcindor, V., Bastin, B., Boulay, F., Briand, J. B., Sanchez-Benitez, A. M., Bouzomita, H., Borcea, C., Borcea, R., Blank, B. B., Carniol, B., Čeliković, I. T., Delahaye, P., Delaunay, F., Etasse, D., Fremont, G., de France, G., Fontbonne, J. M., Grinyer, G. F., Harang, J., Hommet, J., Jevremović, A. M., Lewitowicz, M., Martel, I., Mrazek, J., Parlog, M., Poincheval, J., Ramos, D., Spitaels, C., Stanoiu, M., Thomas, J.,& Toprek, D.. (2017). High precision measurement of the Ne-19 beta-decay half-life using real-time digital acquisition. in Physical Review C, 96(6).
https://doi.org/10.1103/PhysRevC.96.065501

Fontbonne C, Ujić P, de Oliveira Santos F, Flechard X, Rotaru F, Achouri LN, Girard Alcindor V, Bastin B, Boulay F, Briand JB, Sanchez-Benitez AM, Bouzomita H, Borcea C, Borcea R, Blank BB, Carniol B, Čeliković IT, Delahaye P, Delaunay F, Etasse D, Fremont G, de France G, Fontbonne JM, Grinyer GF, Harang J, Hommet J, Jevremović AM, Lewitowicz M, Martel I, Mrazek J, Parlog M, Poincheval J, Ramos D, Spitaels C, Stanoiu M, Thomas J, Toprek D. High precision measurement of the Ne-19 beta-decay half-life using real-time digital acquisition. in Physical Review C. 2017;96(6).
doi:10.1103/PhysRevC.96.065501 .

Fontbonne, C., Ujić, Predrag, de Oliveira Santos, F., Flechard, Xavier, Rotaru, Florin, Achouri, Lynda N., Girard Alcindor, V., Bastin, Beyhan, Boulay, Francois, Briand, J. B., Sanchez-Benitez, Angel Miguel, Bouzomita, H., Borcea, Catalin, Borcea, Ruxandra, Blank, Bertram B., Carniol, Benjamin, Čeliković, Igor T., Delahaye, Pierre, Delaunay, F., Etasse, David, Fremont, Georges, de France, Gilles, Fontbonne, Jean Marc, Grinyer, G. F., Harang, J., Hommet, Jean, Jevremović, Aleksandar M., Lewitowicz, Marek, Martel, Ismael, Mrazek, Jaromir, Parlog, Marian, Poincheval, J., Ramos, Diego, Spitaels, C., Stanoiu, Mihai, Thomas, Jean-Charles, Toprek, Dragan, "High precision measurement of the Ne-19 beta-decay half-life using real-time digital acquisition" in Physical Review C, 96, no. 6 (2017),
https://doi.org/10.1103/PhysRevC.96.065501 . .

TY  - JOUR
AU  - Toprek, Dragan
AU  - Koteski, Vasil J.
AU  - Belošević-Čavor, Jelena
AU  - Ivanovski, Valentin N.
AU  - Umićević, Ana
PY  - 2017
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1834
AB  - In this paper we investigated the effects of Fe-doping of the anatase TiO2 (1 0 1) surface on the crystal structure, electronic and optical properties, and impurity formation energy by means of density functional theory (DFT). The calculations were performed by the SIESTA DFT code and were carried out by using Troullier-Martins pseudopotentials for the 12-electron valence configuration (3s(2)3p(6)3d(2)4s(2)) of Ti atom, 6-electron valence configuration (2s(2)p(4)) of O atom and 8-electron valence configuration (3d(6)4s(2)) of Fe atom. We used a double- zeta basis set including polarization functions. All calculations were spin-polarized. The mechanism of narrowing the band gap and increasing the photocatalytic activity in the visible light region, of the doped TiO2 is discussed by investigating the density of state. The band gap decreases as the concentration of the dopant increases. The Partial Density of States (PDOS) is not the same in the case of spin-up state or spin-down state. Enhanced optical absorption, for light polarized in the z direction (parallel to the surface normal) is clearly observed for Fe doped as compared to the pure anatase TiO2 and the optical absorption is found to increase with the increase in the Fe concentration. The DFT results indicate that the source of the increasing photocatalytic activity in the visible light region of the Fe doped material is due to the introduction of additional electronic states within the band gap. Since the Fe atoms are more stable in Ti substitutional lattice positions for the entire range of Fermi energy E-F over the band gap, only this substitutional position is considered. We hope that our results will highlight a route to improved electronic and optical properties of anatase TiO2 for industrial applications. (C) 2017 Elsevier B.V. All rights reserved.
T2  - Computational and Theoretical Chemistry
T1  - Ab initio study of electronic and optical properties of Fe doped anatase TiO2 (101) surface
VL  - 1120
SP  - 17
EP  - 23
DO  - 10.1016/j.comptc.2017.09.024
ER  - 

@article{
author = "Toprek, Dragan and Koteski, Vasil J. and Belošević-Čavor, Jelena and Ivanovski, Valentin N. and Umićević, Ana",
year = "2017",
abstract = "In this paper we investigated the effects of Fe-doping of the anatase TiO2 (1 0 1) surface on the crystal structure, electronic and optical properties, and impurity formation energy by means of density functional theory (DFT). The calculations were performed by the SIESTA DFT code and were carried out by using Troullier-Martins pseudopotentials for the 12-electron valence configuration (3s(2)3p(6)3d(2)4s(2)) of Ti atom, 6-electron valence configuration (2s(2)p(4)) of O atom and 8-electron valence configuration (3d(6)4s(2)) of Fe atom. We used a double- zeta basis set including polarization functions. All calculations were spin-polarized. The mechanism of narrowing the band gap and increasing the photocatalytic activity in the visible light region, of the doped TiO2 is discussed by investigating the density of state. The band gap decreases as the concentration of the dopant increases. The Partial Density of States (PDOS) is not the same in the case of spin-up state or spin-down state. Enhanced optical absorption, for light polarized in the z direction (parallel to the surface normal) is clearly observed for Fe doped as compared to the pure anatase TiO2 and the optical absorption is found to increase with the increase in the Fe concentration. The DFT results indicate that the source of the increasing photocatalytic activity in the visible light region of the Fe doped material is due to the introduction of additional electronic states within the band gap. Since the Fe atoms are more stable in Ti substitutional lattice positions for the entire range of Fermi energy E-F over the band gap, only this substitutional position is considered. We hope that our results will highlight a route to improved electronic and optical properties of anatase TiO2 for industrial applications. (C) 2017 Elsevier B.V. All rights reserved.",
journal = "Computational and Theoretical Chemistry",
title = "Ab initio study of electronic and optical properties of Fe doped anatase TiO2 (101) surface",
volume = "1120",
pages = "17-23",
doi = "10.1016/j.comptc.2017.09.024"
}

Toprek, D., Koteski, V. J., Belošević-Čavor, J., Ivanovski, V. N.,& Umićević, A.. (2017). Ab initio study of electronic and optical properties of Fe doped anatase TiO2 (101) surface. in Computational and Theoretical Chemistry, 1120, 17-23.
https://doi.org/10.1016/j.comptc.2017.09.024

Toprek D, Koteski VJ, Belošević-Čavor J, Ivanovski VN, Umićević A. Ab initio study of electronic and optical properties of Fe doped anatase TiO2 (101) surface. in Computational and Theoretical Chemistry. 2017;1120:17-23.
doi:10.1016/j.comptc.2017.09.024 .

Toprek, Dragan, Koteski, Vasil J., Belošević-Čavor, Jelena, Ivanovski, Valentin N., Umićević, Ana, "Ab initio study of electronic and optical properties of Fe doped anatase TiO2 (101) surface" in Computational and Theoretical Chemistry, 1120 (2017):17-23,
https://doi.org/10.1016/j.comptc.2017.09.024 . .

TY  - JOUR
AU  - Koteski, Vasil J.
AU  - Belošević-Čavor, Jelena
AU  - Umićević, Ana
AU  - Ivanovski, Valentin N.
AU  - Toprek, Dragan
PY  - 2017
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1721
AB  - Substitutionally and interstitially Cu/Nco-doped anatase TiO2(101) surface is investigated by using density functional theory (DFT) calculations. The results suggest improved visible light photocatalytic activity over undoped anatase TiO2. Sizable lattice relaxation around the dopants is observed, followed by a formation of N-O bond. Depending on the local arrangement of atoms, localized states above the valence band maximum, deep into the band gap, and below the conduction band minimum are found. In addition, our calculation also predict band gap narrowing. The hybridization of the Cu 3d and N 2p states within the band gap and the other electronic and optical properties suggest a synergistic effect of the dopants in the enhancement of the visible light absorption on the (101) anatase surface. (C) 2017 Elsevier B.V. All rights reserved.
T2  - Applied Surface Science
T1  - Improving the photocatalytic properties of anatase TiO2(101) surface by co-doping with Cu and N: Ab initio study
VL  - 425
SP  - 1095
EP  - 1100
DO  - 10.1016/j.apsusc.2017.07.064
ER  - 

@article{
author = "Koteski, Vasil J. and Belošević-Čavor, Jelena and Umićević, Ana and Ivanovski, Valentin N. and Toprek, Dragan",
year = "2017",
abstract = "Substitutionally and interstitially Cu/Nco-doped anatase TiO2(101) surface is investigated by using density functional theory (DFT) calculations. The results suggest improved visible light photocatalytic activity over undoped anatase TiO2. Sizable lattice relaxation around the dopants is observed, followed by a formation of N-O bond. Depending on the local arrangement of atoms, localized states above the valence band maximum, deep into the band gap, and below the conduction band minimum are found. In addition, our calculation also predict band gap narrowing. The hybridization of the Cu 3d and N 2p states within the band gap and the other electronic and optical properties suggest a synergistic effect of the dopants in the enhancement of the visible light absorption on the (101) anatase surface. (C) 2017 Elsevier B.V. All rights reserved.",
journal = "Applied Surface Science",
title = "Improving the photocatalytic properties of anatase TiO2(101) surface by co-doping with Cu and N: Ab initio study",
volume = "425",
pages = "1095-1100",
doi = "10.1016/j.apsusc.2017.07.064"
}

Koteski, V. J., Belošević-Čavor, J., Umićević, A., Ivanovski, V. N.,& Toprek, D.. (2017). Improving the photocatalytic properties of anatase TiO2(101) surface by co-doping with Cu and N: Ab initio study. in Applied Surface Science, 425, 1095-1100.
https://doi.org/10.1016/j.apsusc.2017.07.064

Koteski VJ, Belošević-Čavor J, Umićević A, Ivanovski VN, Toprek D. Improving the photocatalytic properties of anatase TiO2(101) surface by co-doping with Cu and N: Ab initio study. in Applied Surface Science. 2017;425:1095-1100.
doi:10.1016/j.apsusc.2017.07.064 .

Koteski, Vasil J., Belošević-Čavor, Jelena, Umićević, Ana, Ivanovski, Valentin N., Toprek, Dragan, "Improving the photocatalytic properties of anatase TiO2(101) surface by co-doping with Cu and N: Ab initio study" in Applied Surface Science, 425 (2017):1095-1100,
https://doi.org/10.1016/j.apsusc.2017.07.064 . .

TY  - JOUR
AU  - Koteski, Vasil J.
AU  - Ivanovski, Valentin N.
AU  - Umićević, Ana
AU  - Belošević-Čavor, Jelena
AU  - Toprek, Dragan
AU  - Mahnke, Heinz-Eberhard
PY  - 2017
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1688
AB  - Magnetic ground states, local crystallographic environment of Fe, and hyperfine interaction parameters in tetragonal FeX (X = S, Se, Te) are investigated by means of density functional theory (DFT) calculations using augmented plane waves plus local orbitals (APW + lo) method. We use several different magnetic configurations to evaluate the magnetic and electronic properties of this system, as well as the hyperfine interaction parameters at Fe lattice site. The results obtained for the ground state collinear anti-ferromagnetic arrangement relatively well reproduce the quadrupole splitting and isomer shifts from the available Mossbauer measurements. The Baders atoms in molecule charge density analysis indicates bonding of closed-shell type and a sizable charge transfer from Fe to X. The system properties are sensitive to the structural optimization of the position of the chalcogen atom with respect to the iron plane. (C) 2017 Elsevier B.V. All rights reserved.
T2  - Journal of Magnetism and Magnetic Materials
T1  - First-principles calculations of tetragonal FeX (X = S, Se, Te): Magnetism, hyperfine-interaction, and bonding
VL  - 441
SP  - 769
EP  - 775
DO  - 10.1016/j.jmmm.2017.06.092
ER  - 

@article{
author = "Koteski, Vasil J. and Ivanovski, Valentin N. and Umićević, Ana and Belošević-Čavor, Jelena and Toprek, Dragan and Mahnke, Heinz-Eberhard",
year = "2017",
abstract = "Magnetic ground states, local crystallographic environment of Fe, and hyperfine interaction parameters in tetragonal FeX (X = S, Se, Te) are investigated by means of density functional theory (DFT) calculations using augmented plane waves plus local orbitals (APW + lo) method. We use several different magnetic configurations to evaluate the magnetic and electronic properties of this system, as well as the hyperfine interaction parameters at Fe lattice site. The results obtained for the ground state collinear anti-ferromagnetic arrangement relatively well reproduce the quadrupole splitting and isomer shifts from the available Mossbauer measurements. The Baders atoms in molecule charge density analysis indicates bonding of closed-shell type and a sizable charge transfer from Fe to X. The system properties are sensitive to the structural optimization of the position of the chalcogen atom with respect to the iron plane. (C) 2017 Elsevier B.V. All rights reserved.",
journal = "Journal of Magnetism and Magnetic Materials",
title = "First-principles calculations of tetragonal FeX (X = S, Se, Te): Magnetism, hyperfine-interaction, and bonding",
volume = "441",
pages = "769-775",
doi = "10.1016/j.jmmm.2017.06.092"
}

Koteski, V. J., Ivanovski, V. N., Umićević, A., Belošević-Čavor, J., Toprek, D.,& Mahnke, H.. (2017). First-principles calculations of tetragonal FeX (X = S, Se, Te): Magnetism, hyperfine-interaction, and bonding. in Journal of Magnetism and Magnetic Materials, 441, 769-775.
https://doi.org/10.1016/j.jmmm.2017.06.092

Koteski VJ, Ivanovski VN, Umićević A, Belošević-Čavor J, Toprek D, Mahnke H. First-principles calculations of tetragonal FeX (X = S, Se, Te): Magnetism, hyperfine-interaction, and bonding. in Journal of Magnetism and Magnetic Materials. 2017;441:769-775.
doi:10.1016/j.jmmm.2017.06.092 .

Koteski, Vasil J., Ivanovski, Valentin N., Umićević, Ana, Belošević-Čavor, Jelena, Toprek, Dragan, Mahnke, Heinz-Eberhard, "First-principles calculations of tetragonal FeX (X = S, Se, Te): Magnetism, hyperfine-interaction, and bonding" in Journal of Magnetism and Magnetic Materials, 441 (2017):769-775,
https://doi.org/10.1016/j.jmmm.2017.06.092 . .

TY  - JOUR
AU  - Dey, Sandhya K.
AU  - Dey, Chandi Charan
AU  - Saha, Saibal
AU  - Belošević-Čavor, Jelena
AU  - Toprek, Dragan
PY  - 2017
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1668
AB  - Time-differential perturbed angular correlation (TDPAC) measurements have been carried out in stoichiometric ZrNi3 and HfNi3 intermetallic compounds using Ta-181 probe in the temperature range 77-1073 K considering the immense technological applications of Zr-Ni and Hf-Ni intermetallic compounds. In ZrNi3, four components due to the production of Zr2Ni7, Zr8Ni21, Zr7Ni10 and ZrNi3 have been found at room temperature. The HfNi3 sample produces five electric quadrupole interaction frequencies at room temperature. The phase HfNi3 is strongly produced in stoichiometric sample of HfNi3 where two non-equivalent Hf sites are found to be present. Besides this phase, two other phases due to Hf2Ni7 and Hf8Ni21 have been found but, we do not observe any phase due to Hf7Ni10. X-ray diffraction, TEM/energy dispersive X-ray spectroscopy (EDX) and TEM-selected area electron diffraction (SAED) measurements were used to further characterize the investigated materials and it was found that these results agree with the TDPAC results. In order to confirm findings from TDPAC measurements, density functional theory (DFT) based calculations of electric field gradients (EFG) and asymmetry parameters at the sites of Ta-181 probe nucleus were performed. Our calculated results are found to be in excellent agreement with the experimental results. (C) 2017 Elsevier B.V. All rights reserved.
T2  - Journal of Alloys and Compounds
T1  - Identification of phase components in Zr-Ni and Hf-Ni intermetallic compounds; investigations by perturbed angular correlation spectroscopy and first principles calculations
VL  - 723
SP  - 425
EP  - 433
DO  - 10.1016/j.jallcom.2017.06.227
ER  - 

@article{
author = "Dey, Sandhya K. and Dey, Chandi Charan and Saha, Saibal and Belošević-Čavor, Jelena and Toprek, Dragan",
year = "2017",
abstract = "Time-differential perturbed angular correlation (TDPAC) measurements have been carried out in stoichiometric ZrNi3 and HfNi3 intermetallic compounds using Ta-181 probe in the temperature range 77-1073 K considering the immense technological applications of Zr-Ni and Hf-Ni intermetallic compounds. In ZrNi3, four components due to the production of Zr2Ni7, Zr8Ni21, Zr7Ni10 and ZrNi3 have been found at room temperature. The HfNi3 sample produces five electric quadrupole interaction frequencies at room temperature. The phase HfNi3 is strongly produced in stoichiometric sample of HfNi3 where two non-equivalent Hf sites are found to be present. Besides this phase, two other phases due to Hf2Ni7 and Hf8Ni21 have been found but, we do not observe any phase due to Hf7Ni10. X-ray diffraction, TEM/energy dispersive X-ray spectroscopy (EDX) and TEM-selected area electron diffraction (SAED) measurements were used to further characterize the investigated materials and it was found that these results agree with the TDPAC results. In order to confirm findings from TDPAC measurements, density functional theory (DFT) based calculations of electric field gradients (EFG) and asymmetry parameters at the sites of Ta-181 probe nucleus were performed. Our calculated results are found to be in excellent agreement with the experimental results. (C) 2017 Elsevier B.V. All rights reserved.",
journal = "Journal of Alloys and Compounds",
title = "Identification of phase components in Zr-Ni and Hf-Ni intermetallic compounds; investigations by perturbed angular correlation spectroscopy and first principles calculations",
volume = "723",
pages = "425-433",
doi = "10.1016/j.jallcom.2017.06.227"
}

Dey, S. K., Dey, C. C., Saha, S., Belošević-Čavor, J.,& Toprek, D.. (2017). Identification of phase components in Zr-Ni and Hf-Ni intermetallic compounds; investigations by perturbed angular correlation spectroscopy and first principles calculations. in Journal of Alloys and Compounds, 723, 425-433.
https://doi.org/10.1016/j.jallcom.2017.06.227

Dey SK, Dey CC, Saha S, Belošević-Čavor J, Toprek D. Identification of phase components in Zr-Ni and Hf-Ni intermetallic compounds; investigations by perturbed angular correlation spectroscopy and first principles calculations. in Journal of Alloys and Compounds. 2017;723:425-433.
doi:10.1016/j.jallcom.2017.06.227 .

Dey, Sandhya K., Dey, Chandi Charan, Saha, Saibal, Belošević-Čavor, Jelena, Toprek, Dragan, "Identification of phase components in Zr-Ni and Hf-Ni intermetallic compounds; investigations by perturbed angular correlation spectroscopy and first principles calculations" in Journal of Alloys and Compounds, 723 (2017):425-433,
https://doi.org/10.1016/j.jallcom.2017.06.227 . .

TY  - JOUR
AU  - Čevizović, Dalibor
AU  - Ivić, Zoran
AU  - Toprek, Dragan
AU  - Pržulj, Željko
AU  - Kapor, Darko
PY  - 2016
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1275
AB  - We consider the properties of the large acoustic polarons in a media composed of three parallel coupled identical macromolecular chains in an equilateral triangular arrangement. The existence of the truly three-dimensional large polarons has been demonstrated. Their appearance demands the complex interference of the effects of the reduced dimensionality, the nature and strength of the interchain coupling and particular geometrical arrangement of molecular chains. Different types of solutions were found and criteria for their existence were formulated in terms of the dimensionless interchain coupling parameter. (C) 2016 Elsevier Ltd. All rights reserved.
T2  - Chaos, Solitons and Fractals
T1  - Large acoustic polaron states and bifurcation in three coupled parallel molecular chains
VL  - 91
SP  - 63
EP  - 68
DO  - 10.1016/j.chaos.2016.05.001
ER  - 

@article{
author = "Čevizović, Dalibor and Ivić, Zoran and Toprek, Dragan and Pržulj, Željko and Kapor, Darko",
year = "2016",
abstract = "We consider the properties of the large acoustic polarons in a media composed of three parallel coupled identical macromolecular chains in an equilateral triangular arrangement. The existence of the truly three-dimensional large polarons has been demonstrated. Their appearance demands the complex interference of the effects of the reduced dimensionality, the nature and strength of the interchain coupling and particular geometrical arrangement of molecular chains. Different types of solutions were found and criteria for their existence were formulated in terms of the dimensionless interchain coupling parameter. (C) 2016 Elsevier Ltd. All rights reserved.",
journal = "Chaos, Solitons and Fractals",
title = "Large acoustic polaron states and bifurcation in three coupled parallel molecular chains",
volume = "91",
pages = "63-68",
doi = "10.1016/j.chaos.2016.05.001"
}

Čevizović, D., Ivić, Z., Toprek, D., Pržulj, Ž.,& Kapor, D.. (2016). Large acoustic polaron states and bifurcation in three coupled parallel molecular chains. in Chaos, Solitons and Fractals, 91, 63-68.
https://doi.org/10.1016/j.chaos.2016.05.001

Čevizović D, Ivić Z, Toprek D, Pržulj Ž, Kapor D. Large acoustic polaron states and bifurcation in three coupled parallel molecular chains. in Chaos, Solitons and Fractals. 2016;91:63-68.
doi:10.1016/j.chaos.2016.05.001 .

Čevizović, Dalibor, Ivić, Zoran, Toprek, Dragan, Pržulj, Željko, Kapor, Darko, "Large acoustic polaron states and bifurcation in three coupled parallel molecular chains" in Chaos, Solitons and Fractals, 91 (2016):63-68,
https://doi.org/10.1016/j.chaos.2016.05.001 . .

TY  - JOUR
AU  - Toprek, Dragan
AU  - Koteski, Vasil J.
PY  - 2016
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/981
AB  - The stability and structure of titanium doped gold clusters (AunTi; n = 1-32) are studied by density functional theory calculations, as implemented in the first principles code SIESTA. The exchange and correlation effects were calculated within the generalized gradient approximation (GGA) parametrized by Perdew, Burke and Ernzerhof (PBE). We used norm conserving Troullier-Martins pseudopotentials for the 10-electron valence configuration of Ti and 11-electron valence configuration of Au. All calculations were spin-polarized. The global energy minimum geometries of the clusters were searched for by using the simulated annealing technique. The stability of the clusters is discussed on the basis of the binding energy per atom, second-order energy difference, vertical ionization potential, vertical electron affinities, HOMO-LUMO energy gap and vibrational frequencies. Based on the simultaneous criteria of high binding energy, high band gap, high vertical ionization potential, and low electron affinity, it is found that Au4Ti and Au14Ti clusters have a higher stability and are candidates for magic clusters, which confirms the already known results from previous works. The new result presented in this paper is that the Au20Ti and Au30Ti clusters have a higher stability too. In general, the clusters with even n are more stable than the clusters with odd n. Most of the clusters with even n are non-magnetic (total magnetic moment is zero). Our results also suggest that only the Au3Ti, Au7Ti and Au8Ti clusters have a planar structure. (C) 2016 Elsevier B.V. All rights reserved.
PB  - Elsevier
T2  - Computational and Theoretical Chemistry
T1  - Ab initio calculations of the structure, energetics and stability of AunTi (n=1-32) clusters
VL  - 1081
SP  - 9
EP  - 17
DO  - 10.1016/j.comptc.2016.02.005
ER  - 

@article{
author = "Toprek, Dragan and Koteski, Vasil J.",
year = "2016",
abstract = "The stability and structure of titanium doped gold clusters (AunTi; n = 1-32) are studied by density functional theory calculations, as implemented in the first principles code SIESTA. The exchange and correlation effects were calculated within the generalized gradient approximation (GGA) parametrized by Perdew, Burke and Ernzerhof (PBE). We used norm conserving Troullier-Martins pseudopotentials for the 10-electron valence configuration of Ti and 11-electron valence configuration of Au. All calculations were spin-polarized. The global energy minimum geometries of the clusters were searched for by using the simulated annealing technique. The stability of the clusters is discussed on the basis of the binding energy per atom, second-order energy difference, vertical ionization potential, vertical electron affinities, HOMO-LUMO energy gap and vibrational frequencies. Based on the simultaneous criteria of high binding energy, high band gap, high vertical ionization potential, and low electron affinity, it is found that Au4Ti and Au14Ti clusters have a higher stability and are candidates for magic clusters, which confirms the already known results from previous works. The new result presented in this paper is that the Au20Ti and Au30Ti clusters have a higher stability too. In general, the clusters with even n are more stable than the clusters with odd n. Most of the clusters with even n are non-magnetic (total magnetic moment is zero). Our results also suggest that only the Au3Ti, Au7Ti and Au8Ti clusters have a planar structure. (C) 2016 Elsevier B.V. All rights reserved.",
publisher = "Elsevier",
journal = "Computational and Theoretical Chemistry",
title = "Ab initio calculations of the structure, energetics and stability of AunTi (n=1-32) clusters",
volume = "1081",
pages = "9-17",
doi = "10.1016/j.comptc.2016.02.005"
}

Toprek, D.,& Koteski, V. J.. (2016). Ab initio calculations of the structure, energetics and stability of AunTi (n=1-32) clusters. in Computational and Theoretical Chemistry
Elsevier., 1081, 9-17.
https://doi.org/10.1016/j.comptc.2016.02.005

Toprek D, Koteski VJ. Ab initio calculations of the structure, energetics and stability of AunTi (n=1-32) clusters. in Computational and Theoretical Chemistry. 2016;1081:9-17.
doi:10.1016/j.comptc.2016.02.005 .

Toprek, Dragan, Koteski, Vasil J., "Ab initio calculations of the structure, energetics and stability of AunTi (n=1-32) clusters" in Computational and Theoretical Chemistry, 1081 (2016):9-17,
https://doi.org/10.1016/j.comptc.2016.02.005 . .

TY  - JOUR
AU  - Čevizović, Dalibor
AU  - Ivić, Zoran
AU  - Toprek, Dragan
AU  - Kapor, Darko
AU  - Pržulj, Željko
PY  - 2015
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/478
AB  - We study the properties of the single large adiabatic polaron in the substances composed of three parallel equally separated coplanar molecular chains. Particular attention has been devoted to the influence of the interchain coupling strength on polaron stability in order to elucidate the origin of the large polaron existence, which, contrary to the predictions of continuum adiabatic theories may persist in realistic conditions. Our results indicate the existence of the effectively two-dimensional stationary polarons with comparably large longitudinal radius while the transverse one ranges from zero, in the absence of interchain coupling, to approximately twice of the interchain separation when coupling strength tends towards the infinity. These two-dimensional polarons are both energetically and dynamically stable. This is quite the opposite to the expectations based on the traditional adiabatic large polaron theories which, in the case of short ranged electron phonon interaction, predict that the stable large polaron may exist only in 1D systems. Stability of these 2D polarons increases with the increase of the interchain coupling strength so that they may be comparably more stable than the pure 1D polarons. (C) 2015 Elsevier Ltd. All rights reserved.
T2  - Chaos, Solitons and Fractals
T1  - The influence of the interchain coupling on large acoustic polarons in coupled molecular chains: Three coplanar parallel molecular chains
VL  - 73
SP  - 71
EP  - 79
DO  - 10.1016/j.chaos.2015.01.002
ER  - 

@article{
author = "Čevizović, Dalibor and Ivić, Zoran and Toprek, Dragan and Kapor, Darko and Pržulj, Željko",
year = "2015",
abstract = "We study the properties of the single large adiabatic polaron in the substances composed of three parallel equally separated coplanar molecular chains. Particular attention has been devoted to the influence of the interchain coupling strength on polaron stability in order to elucidate the origin of the large polaron existence, which, contrary to the predictions of continuum adiabatic theories may persist in realistic conditions. Our results indicate the existence of the effectively two-dimensional stationary polarons with comparably large longitudinal radius while the transverse one ranges from zero, in the absence of interchain coupling, to approximately twice of the interchain separation when coupling strength tends towards the infinity. These two-dimensional polarons are both energetically and dynamically stable. This is quite the opposite to the expectations based on the traditional adiabatic large polaron theories which, in the case of short ranged electron phonon interaction, predict that the stable large polaron may exist only in 1D systems. Stability of these 2D polarons increases with the increase of the interchain coupling strength so that they may be comparably more stable than the pure 1D polarons. (C) 2015 Elsevier Ltd. All rights reserved.",
journal = "Chaos, Solitons and Fractals",
title = "The influence of the interchain coupling on large acoustic polarons in coupled molecular chains: Three coplanar parallel molecular chains",
volume = "73",
pages = "71-79",
doi = "10.1016/j.chaos.2015.01.002"
}

Čevizović, D., Ivić, Z., Toprek, D., Kapor, D.,& Pržulj, Ž.. (2015). The influence of the interchain coupling on large acoustic polarons in coupled molecular chains: Three coplanar parallel molecular chains. in Chaos, Solitons and Fractals, 73, 71-79.
https://doi.org/10.1016/j.chaos.2015.01.002

Čevizović D, Ivić Z, Toprek D, Kapor D, Pržulj Ž. The influence of the interchain coupling on large acoustic polarons in coupled molecular chains: Three coplanar parallel molecular chains. in Chaos, Solitons and Fractals. 2015;73:71-79.
doi:10.1016/j.chaos.2015.01.002 .

Čevizović, Dalibor, Ivić, Zoran, Toprek, Dragan, Kapor, Darko, Pržulj, Željko, "The influence of the interchain coupling on large acoustic polarons in coupled molecular chains: Three coplanar parallel molecular chains" in Chaos, Solitons and Fractals, 73 (2015):71-79,
https://doi.org/10.1016/j.chaos.2015.01.002 . .

TY  - JOUR
AU  - Toprek, Dragan
AU  - Belošević-Čavor, Jelena
AU  - Koteski, Vasil J.
PY  - 2015
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/678
AB  - First principles calculations were performed in the framework of the density functional theory (DFF) using the Full Potential-Linear Augment Plane Wave method (FP-LAPW) within the generalized gradient approximation (GGA) to predict the structural, electronic, elastic and thermal properties of NiTi2 intermetallic compound. By using the Wien2k all-electron code, calculations of the ground state and electronic properties such as lattice constants, bulk modulus, presure derivative of bulk modulus, total energies and density of states were also included. The elastic constants and mechanical properties such as Poissons ratio, Youngs modulus and shear modulus are estimated from the calculated elastic constants of the single crystal. Through the quasi-harmonic Debye model, the preasure and temperature dependences of the linear expansion coefficient, bulk modulus and heat capacity have been investigated. Finally, the Debye temperature has been estimated from the average sound velocity according to the predicted polycrystal bulk properties and from the single crystal elastic constants. (C) 2015 Elsevier Ltd. All rights reserved.
T2  - Journal of Physics and Chemistry of Solids
T1  - Ab initio studies of the structural, elastic, electronic and thermal properties of NiTi2 intermetallic
VL  - 85
SP  - 197
EP  - 205
DO  - 10.1016/j.jpcs.2015.05.019
ER  - 

@article{
author = "Toprek, Dragan and Belošević-Čavor, Jelena and Koteski, Vasil J.",
year = "2015",
abstract = "First principles calculations were performed in the framework of the density functional theory (DFF) using the Full Potential-Linear Augment Plane Wave method (FP-LAPW) within the generalized gradient approximation (GGA) to predict the structural, electronic, elastic and thermal properties of NiTi2 intermetallic compound. By using the Wien2k all-electron code, calculations of the ground state and electronic properties such as lattice constants, bulk modulus, presure derivative of bulk modulus, total energies and density of states were also included. The elastic constants and mechanical properties such as Poissons ratio, Youngs modulus and shear modulus are estimated from the calculated elastic constants of the single crystal. Through the quasi-harmonic Debye model, the preasure and temperature dependences of the linear expansion coefficient, bulk modulus and heat capacity have been investigated. Finally, the Debye temperature has been estimated from the average sound velocity according to the predicted polycrystal bulk properties and from the single crystal elastic constants. (C) 2015 Elsevier Ltd. All rights reserved.",
journal = "Journal of Physics and Chemistry of Solids",
title = "Ab initio studies of the structural, elastic, electronic and thermal properties of NiTi2 intermetallic",
volume = "85",
pages = "197-205",
doi = "10.1016/j.jpcs.2015.05.019"
}

Toprek, D., Belošević-Čavor, J.,& Koteski, V. J.. (2015). Ab initio studies of the structural, elastic, electronic and thermal properties of NiTi2 intermetallic. in Journal of Physics and Chemistry of Solids, 85, 197-205.
https://doi.org/10.1016/j.jpcs.2015.05.019

Toprek D, Belošević-Čavor J, Koteski VJ. Ab initio studies of the structural, elastic, electronic and thermal properties of NiTi2 intermetallic. in Journal of Physics and Chemistry of Solids. 2015;85:197-205.
doi:10.1016/j.jpcs.2015.05.019 .

Toprek, Dragan, Belošević-Čavor, Jelena, Koteski, Vasil J., "Ab initio studies of the structural, elastic, electronic and thermal properties of NiTi2 intermetallic" in Journal of Physics and Chemistry of Solids, 85 (2015):197-205,
https://doi.org/10.1016/j.jpcs.2015.05.019 . .

TY  - JOUR
AU  - Li, Xiaoni
AU  - Toprek, Dragan
AU  - Yuan, Youjin
AU  - He, Yuan
PY  - 2015
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/530
AB  - In this paper we present the study of the transversal and longitudinal acceptance and the transmission efficiency in the injection, acceleration, and extraction systems in the separated sector cyclotron of the heavy ion research facility in Lanzhou, China. The study of cyclotron acceptance is done for U-238(36+) with energy of 97 MeV/u and for Zn-70(10+) with energy of 5.62 MeV/u under the theoretical isochronous and real magnetic field distribution. From the simulation results it can be seen that the transmission efficiency and the acceptances of separated sector cyclotron can be improved by redesign the curvature of MSI3 deflector or by introducing the magnet shim in MSI3 deflector region to change the distribution of the inner magnetic field.
T2  - Nuclear technology and radiation protection
T1  - The Study of Acceptance and the Transmission Efficiency of Separated Sector Cyclotron
VL  - 30
IS  - 1
SP  - 18
EP  - 22
DO  - 10.2298/NTRP1501018L
ER  - 

@article{
author = "Li, Xiaoni and Toprek, Dragan and Yuan, Youjin and He, Yuan",
year = "2015",
abstract = "In this paper we present the study of the transversal and longitudinal acceptance and the transmission efficiency in the injection, acceleration, and extraction systems in the separated sector cyclotron of the heavy ion research facility in Lanzhou, China. The study of cyclotron acceptance is done for U-238(36+) with energy of 97 MeV/u and for Zn-70(10+) with energy of 5.62 MeV/u under the theoretical isochronous and real magnetic field distribution. From the simulation results it can be seen that the transmission efficiency and the acceptances of separated sector cyclotron can be improved by redesign the curvature of MSI3 deflector or by introducing the magnet shim in MSI3 deflector region to change the distribution of the inner magnetic field.",
journal = "Nuclear technology and radiation protection",
title = "The Study of Acceptance and the Transmission Efficiency of Separated Sector Cyclotron",
volume = "30",
number = "1",
pages = "18-22",
doi = "10.2298/NTRP1501018L"
}

Li, X., Toprek, D., Yuan, Y.,& He, Y.. (2015). The Study of Acceptance and the Transmission Efficiency of Separated Sector Cyclotron. in Nuclear technology and radiation protection, 30(1), 18-22.
https://doi.org/10.2298/NTRP1501018L

Li X, Toprek D, Yuan Y, He Y. The Study of Acceptance and the Transmission Efficiency of Separated Sector Cyclotron. in Nuclear technology and radiation protection. 2015;30(1):18-22.
doi:10.2298/NTRP1501018L .

Li, Xiaoni, Toprek, Dragan, Yuan, Youjin, He, Yuan, "The Study of Acceptance and the Transmission Efficiency of Separated Sector Cyclotron" in Nuclear technology and radiation protection, 30, no. 1 (2015):18-22,
https://doi.org/10.2298/NTRP1501018L . .

TY  - JOUR
AU  - Toprek, Dragan
PY  - 2014
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/241
AB  - In this paper the detailed structure of the transport beam line design is proposed, quadrupoles and deflectors specifications in order to transport the beam from the optic adaptation point in the SPIRAL2 production building up to the adaptation point in the DESIR hall. All optical elements, in beam line, are electrostatic and so, settings are independent of the ratio q/m of the particle. The calculations are done by COSY INFINITY computer code in first order of approximation and without fringe field effects. The beam emittances at the starting point (adaptation point in the SPIRAL2 production building) in horizontal and vertical planes are 80 pi nun mrad. The beam line is designed in such a way that the beam sizes, in both planes, at the end (adaptation point in the DESIR hall) are kept the same as they are at the starting point; the horizontal and vertical displacements from the optic axis at starting and ending points are the same, +/- 6 mm. In such case the efficiency of transport of the beam is high.
T2  - Nuclear technology and radiation protection
T1  - Proposed Transport Beam Line for Desir
VL  - 29
IS  - 3
SP  - 171
EP  - 178
DO  - 10.2298/NTRP1403171T
ER  - 

@article{
author = "Toprek, Dragan",
year = "2014",
abstract = "In this paper the detailed structure of the transport beam line design is proposed, quadrupoles and deflectors specifications in order to transport the beam from the optic adaptation point in the SPIRAL2 production building up to the adaptation point in the DESIR hall. All optical elements, in beam line, are electrostatic and so, settings are independent of the ratio q/m of the particle. The calculations are done by COSY INFINITY computer code in first order of approximation and without fringe field effects. The beam emittances at the starting point (adaptation point in the SPIRAL2 production building) in horizontal and vertical planes are 80 pi nun mrad. The beam line is designed in such a way that the beam sizes, in both planes, at the end (adaptation point in the DESIR hall) are kept the same as they are at the starting point; the horizontal and vertical displacements from the optic axis at starting and ending points are the same, +/- 6 mm. In such case the efficiency of transport of the beam is high.",
journal = "Nuclear technology and radiation protection",
title = "Proposed Transport Beam Line for Desir",
volume = "29",
number = "3",
pages = "171-178",
doi = "10.2298/NTRP1403171T"
}

Toprek, D.. (2014). Proposed Transport Beam Line for Desir. in Nuclear technology and radiation protection, 29(3), 171-178.
https://doi.org/10.2298/NTRP1403171T

Toprek D. Proposed Transport Beam Line for Desir. in Nuclear technology and radiation protection. 2014;29(3):171-178.
doi:10.2298/NTRP1403171T .

Toprek, Dragan, "Proposed Transport Beam Line for Desir" in Nuclear technology and radiation protection, 29, no. 3 (2014):171-178,
https://doi.org/10.2298/NTRP1403171T . .

TY  - JOUR
AU  - Milosavljević, Momir
AU  - Toprek, Dragan
AU  - Obradović, Marko O.
AU  - Grce, Ana
AU  - Peruško, Davor
AU  - Dražić, Goran
AU  - Kovač, Janez
AU  - Homewood, Kevin P.
PY  - 2013
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/5335
AB  - The effects of Ar ion irradiation on interfacial reactions induced in Ni/Ti multilayers were investigated. Structures consisting of 10 alternate Ni (similar to 26 nm) and Ti (similar to 20 nm) layers of a total thickness similar to 230 nm were deposited by ion sputtering on Si (1 0 0) wafers. Argon irradiations were done at 180 keV, to the doses of 1-6 x 10(16) ions/cm(2), the samples being held at room temperature. The projected implanted ion range is 86 +/- 36 nm, maximum energy loss is closer to the surface, and maximum displacements per atom (dpa) from 47 to 284 for Ni and 26 to 156 for Ti. Characterizations of samples were performed by transmission electron microscopy (TEM) and Rutherford backscattering spectrometry (RBS). It is shown that ion irradiation induced a progressed intermixing in the mostly affected zone already for the lowest dose, the thickness of the mix increasing linearly with the irradiation dose. The mixed phase is fully amorphous, starting with a higher concentration of Ni (which is the diffusing species) from the initial stages, and saturating at Ni: Ti similar to 66:34. A thick amorphous layer (similar to 127 nm) formed towards the surface region of the structure for the irradiation dose of 4 x 10(16) ions/cm(2) remains stable with increasing the dose to 6 x 10(16) ions/cm(2), which introduces up to 6-7 at.% of Ar within the mix. The results are discussed in light of the existing models. They can be interesting for introducing a selective and controlled solid-state reaction and towards further studies of ion irradiation stability of amorphous Ni-Ti phase. (C) 2013 Elsevier B.V. All rights reserved.
T2  - Applied Surface Science
T1  - Ion irradiation induced solid-state amorphous reaction in Ni/Ti multilayers
VL  - 268
SP  - 516
EP  - 523
DO  - 10.1016/j.apsusc.2012.12.158
ER  - 

@article{
author = "Milosavljević, Momir and Toprek, Dragan and Obradović, Marko O. and Grce, Ana and Peruško, Davor and Dražić, Goran and Kovač, Janez and Homewood, Kevin P.",
year = "2013",
abstract = "The effects of Ar ion irradiation on interfacial reactions induced in Ni/Ti multilayers were investigated. Structures consisting of 10 alternate Ni (similar to 26 nm) and Ti (similar to 20 nm) layers of a total thickness similar to 230 nm were deposited by ion sputtering on Si (1 0 0) wafers. Argon irradiations were done at 180 keV, to the doses of 1-6 x 10(16) ions/cm(2), the samples being held at room temperature. The projected implanted ion range is 86 +/- 36 nm, maximum energy loss is closer to the surface, and maximum displacements per atom (dpa) from 47 to 284 for Ni and 26 to 156 for Ti. Characterizations of samples were performed by transmission electron microscopy (TEM) and Rutherford backscattering spectrometry (RBS). It is shown that ion irradiation induced a progressed intermixing in the mostly affected zone already for the lowest dose, the thickness of the mix increasing linearly with the irradiation dose. The mixed phase is fully amorphous, starting with a higher concentration of Ni (which is the diffusing species) from the initial stages, and saturating at Ni: Ti similar to 66:34. A thick amorphous layer (similar to 127 nm) formed towards the surface region of the structure for the irradiation dose of 4 x 10(16) ions/cm(2) remains stable with increasing the dose to 6 x 10(16) ions/cm(2), which introduces up to 6-7 at.% of Ar within the mix. The results are discussed in light of the existing models. They can be interesting for introducing a selective and controlled solid-state reaction and towards further studies of ion irradiation stability of amorphous Ni-Ti phase. (C) 2013 Elsevier B.V. All rights reserved.",
journal = "Applied Surface Science",
title = "Ion irradiation induced solid-state amorphous reaction in Ni/Ti multilayers",
volume = "268",
pages = "516-523",
doi = "10.1016/j.apsusc.2012.12.158"
}

Milosavljević, M., Toprek, D., Obradović, M. O., Grce, A., Peruško, D., Dražić, G., Kovač, J.,& Homewood, K. P.. (2013). Ion irradiation induced solid-state amorphous reaction in Ni/Ti multilayers. in Applied Surface Science, 268, 516-523.
https://doi.org/10.1016/j.apsusc.2012.12.158

Milosavljević M, Toprek D, Obradović MO, Grce A, Peruško D, Dražić G, Kovač J, Homewood KP. Ion irradiation induced solid-state amorphous reaction in Ni/Ti multilayers. in Applied Surface Science. 2013;268:516-523.
doi:10.1016/j.apsusc.2012.12.158 .

Milosavljević, Momir, Toprek, Dragan, Obradović, Marko O., Grce, Ana, Peruško, Davor, Dražić, Goran, Kovač, Janez, Homewood, Kevin P., "Ion irradiation induced solid-state amorphous reaction in Ni/Ti multilayers" in Applied Surface Science, 268 (2013):516-523,
https://doi.org/10.1016/j.apsusc.2012.12.158 . .

TY  - JOUR
AU  - Toprek, Dragan
AU  - Ivić, Zoran
AU  - Kapor, Darko
AU  - Lekic, Sreten
PY  - 2013
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/5400
AB  - Properties of the large acoustic polarons in discrete molecular chains have been investigated within the adiabatic approximation. It turns out that practically all the polaron features are determined by the single parameter-coupling constant which represents the ratio between the small polaron binding energy and the electron bandwidth. Three different types of stationary solutions were found corresponding to weak, intermediate, and strong coupling limits, respectively. In the weak coupling regime, that is, for the values of coupling constant exceeding the limit of the applicability of continuum approximation but lower than the critical one ( $g_C$), we observe symmetric bond-centered solution corresponding to the polaron positioned in the middle between the adjacent lattice sites. When coupling constant overgrows, this critical value transition toward the site-centered state occurs. It takes place continuously through the intermediate asymmetric state whose position gradually approaches lattice site as coupling constant increases. One of the main consequences of the lattice discreteness is the emergence of the periodic potential, Peierls-Nabarro potential relief, through which polarons have to pass to transfer along the chain. The conditions for the polaron propagation are formulated in terms of the threshold velocity. (c) 2012 Wiley Periodicals, Inc.
T2  - International Journal of Quantum Chemistry
T1  - Stationary polarons in discrete molecular chains
VL  - 113
IS  - 10
SP  - 1522
EP  - 1533
DO  - 10.1002/qua.24353
ER  - 

@article{
author = "Toprek, Dragan and Ivić, Zoran and Kapor, Darko and Lekic, Sreten",
year = "2013",
abstract = "Properties of the large acoustic polarons in discrete molecular chains have been investigated within the adiabatic approximation. It turns out that practically all the polaron features are determined by the single parameter-coupling constant which represents the ratio between the small polaron binding energy and the electron bandwidth. Three different types of stationary solutions were found corresponding to weak, intermediate, and strong coupling limits, respectively. In the weak coupling regime, that is, for the values of coupling constant exceeding the limit of the applicability of continuum approximation but lower than the critical one ( $g_C$), we observe symmetric bond-centered solution corresponding to the polaron positioned in the middle between the adjacent lattice sites. When coupling constant overgrows, this critical value transition toward the site-centered state occurs. It takes place continuously through the intermediate asymmetric state whose position gradually approaches lattice site as coupling constant increases. One of the main consequences of the lattice discreteness is the emergence of the periodic potential, Peierls-Nabarro potential relief, through which polarons have to pass to transfer along the chain. The conditions for the polaron propagation are formulated in terms of the threshold velocity. (c) 2012 Wiley Periodicals, Inc.",
journal = "International Journal of Quantum Chemistry",
title = "Stationary polarons in discrete molecular chains",
volume = "113",
number = "10",
pages = "1522-1533",
doi = "10.1002/qua.24353"
}

Toprek, D., Ivić, Z., Kapor, D.,& Lekic, S.. (2013). Stationary polarons in discrete molecular chains. in International Journal of Quantum Chemistry, 113(10), 1522-1533.
https://doi.org/10.1002/qua.24353

Toprek D, Ivić Z, Kapor D, Lekic S. Stationary polarons in discrete molecular chains. in International Journal of Quantum Chemistry. 2013;113(10):1522-1533.
doi:10.1002/qua.24353 .

Toprek, Dragan, Ivić, Zoran, Kapor, Darko, Lekic, Sreten, "Stationary polarons in discrete molecular chains" in International Journal of Quantum Chemistry, 113, no. 10 (2013):1522-1533,
https://doi.org/10.1002/qua.24353 . .