TY  - JOUR
AU  - Ivić, Zoran
AU  - Zeković, Slobodan
AU  - Čevizović, Dalibor
AU  - Kostić, Dragan
AU  - Vujicic, G
PY  - 2005
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2901
AB  - We study the effect of the small-polaron induced changes of phonon spectra on charge transfer in molecular solids. Noticeable discrepancy with the predictions of the traditional small-polaron theories is observed: accounting of phonon hardening yields significantly lower estimates for small-polaron resistivity than that obtained on the basis of conventional approaches. This especially concerns the low temperature limit in which transport processes are dominated by the band like motion of charge carriers. This difference gradually disappears with the increasing of coupling constant and temperature. (c) 2005 Elsevier B.V. All rights reserved.
T2  - Physica B: Condensed Matter
T1  - Small-polaron resistivity of the narrow band molecular chain: The influence of phonon hardening
VL  - 362
IS  - 1-4
SP  - 187
EP  - 192
DO  - 10.1016/j.physb.2005.02.010
ER  - 

@article{
author = "Ivić, Zoran and Zeković, Slobodan and Čevizović, Dalibor and Kostić, Dragan and Vujicic, G",
year = "2005",
abstract = "We study the effect of the small-polaron induced changes of phonon spectra on charge transfer in molecular solids. Noticeable discrepancy with the predictions of the traditional small-polaron theories is observed: accounting of phonon hardening yields significantly lower estimates for small-polaron resistivity than that obtained on the basis of conventional approaches. This especially concerns the low temperature limit in which transport processes are dominated by the band like motion of charge carriers. This difference gradually disappears with the increasing of coupling constant and temperature. (c) 2005 Elsevier B.V. All rights reserved.",
journal = "Physica B: Condensed Matter",
title = "Small-polaron resistivity of the narrow band molecular chain: The influence of phonon hardening",
volume = "362",
number = "1-4",
pages = "187-192",
doi = "10.1016/j.physb.2005.02.010"
}

Ivić, Z., Zeković, S., Čevizović, D., Kostić, D.,& Vujicic, G.. (2005). Small-polaron resistivity of the narrow band molecular chain: The influence of phonon hardening. in Physica B: Condensed Matter, 362(1-4), 187-192.
https://doi.org/10.1016/j.physb.2005.02.010

Ivić Z, Zeković S, Čevizović D, Kostić D, Vujicic G. Small-polaron resistivity of the narrow band molecular chain: The influence of phonon hardening. in Physica B: Condensed Matter. 2005;362(1-4):187-192.
doi:10.1016/j.physb.2005.02.010 .

Ivić, Zoran, Zeković, Slobodan, Čevizović, Dalibor, Kostić, Dragan, Vujicic, G, "Small-polaron resistivity of the narrow band molecular chain: The influence of phonon hardening" in Physica B: Condensed Matter, 362, no. 1-4 (2005):187-192,
https://doi.org/10.1016/j.physb.2005.02.010 . .

TY  - JOUR
AU  - Ivić, Zoran
AU  - Kostić, Dragan
AU  - Kapor, Darko
PY  - 2005
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2885
AB  - Temperature dependence of the effective tunneling frequency of the spin-phonon model for a few particular types of coupling has been studied within the framework of the simple variational method. Our analysis shows that for the Ohmic type of coupling, temperature drives the system towards delocalization. The same type of behavior has been noticed for super-Ohmic case, but in the so-called adiabatic regime, while in the nonadiabatic case we predict localization transition, analogous to that observed for Ohmic coupling, when temperature dependent coupling constant S(T) approaches critical value S(T) similar to 1/2. In contrast to these results, for super-Ohmic (r = 3) case, there was no substantial difference with respect to zero-temperature case. Brief discussion of the validity of the method has been given. (c) 2005 Published by Elsevier B.V.
T2  - Physics Letters A
T1  - Finite temperature variational analysis of the tunneling and localization in spin-phonon model
VL  - 339
IS  - 3-5
SP  - 393
EP  - 402
DO  - 10.1016/j.physleta.2006.02.067
ER  - 

@article{
author = "Ivić, Zoran and Kostić, Dragan and Kapor, Darko",
year = "2005",
abstract = "Temperature dependence of the effective tunneling frequency of the spin-phonon model for a few particular types of coupling has been studied within the framework of the simple variational method. Our analysis shows that for the Ohmic type of coupling, temperature drives the system towards delocalization. The same type of behavior has been noticed for super-Ohmic case, but in the so-called adiabatic regime, while in the nonadiabatic case we predict localization transition, analogous to that observed for Ohmic coupling, when temperature dependent coupling constant S(T) approaches critical value S(T) similar to 1/2. In contrast to these results, for super-Ohmic (r = 3) case, there was no substantial difference with respect to zero-temperature case. Brief discussion of the validity of the method has been given. (c) 2005 Published by Elsevier B.V.",
journal = "Physics Letters A",
title = "Finite temperature variational analysis of the tunneling and localization in spin-phonon model",
volume = "339",
number = "3-5",
pages = "393-402",
doi = "10.1016/j.physleta.2006.02.067"
}

Ivić, Z., Kostić, D.,& Kapor, D.. (2005). Finite temperature variational analysis of the tunneling and localization in spin-phonon model. in Physics Letters A, 339(3-5), 393-402.
https://doi.org/10.1016/j.physleta.2006.02.067

Ivić Z, Kostić D, Kapor D. Finite temperature variational analysis of the tunneling and localization in spin-phonon model. in Physics Letters A. 2005;339(3-5):393-402.
doi:10.1016/j.physleta.2006.02.067 .

Ivić, Zoran, Kostić, Dragan, Kapor, Darko, "Finite temperature variational analysis of the tunneling and localization in spin-phonon model" in Physics Letters A, 339, no. 3-5 (2005):393-402,
https://doi.org/10.1016/j.physleta.2006.02.067 . .

TY  - JOUR
AU  - Ivić, Zoran
AU  - Zeković, Slobodan
AU  - Čevizović, Dalibor
AU  - Kostić, Dragan
PY  - 2005
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2851
AB  - The influence of the small-polaron effect on the vibrational properties of the strongly coupled electron-phonon system is investigated. It was found that polaron-phonon interaction may cause a noticeable renormalization of the phonon spectra. These changes may be observed by the measurements of the speed of sound for which a very specific dependence on temperature, values of coupling constant and adiabatic parameter is expected. We also found that the rise of the small-polaron effective mass as a function of the coupling constant should be considerably moderated than that anticipated without taking into account the modification of the vibrational spectra. (C) 2004 Elsevier B.V. All rights reserved.
T2  - Physica B: Condensed Matter
T1  - Phonon hardening due to the small-polaron effect
VL  - 355
IS  - 1-4
SP  - 417
EP  - 426
DO  - 10.1016/j.physb.2004.11.070
ER  - 

@article{
author = "Ivić, Zoran and Zeković, Slobodan and Čevizović, Dalibor and Kostić, Dragan",
year = "2005",
abstract = "The influence of the small-polaron effect on the vibrational properties of the strongly coupled electron-phonon system is investigated. It was found that polaron-phonon interaction may cause a noticeable renormalization of the phonon spectra. These changes may be observed by the measurements of the speed of sound for which a very specific dependence on temperature, values of coupling constant and adiabatic parameter is expected. We also found that the rise of the small-polaron effective mass as a function of the coupling constant should be considerably moderated than that anticipated without taking into account the modification of the vibrational spectra. (C) 2004 Elsevier B.V. All rights reserved.",
journal = "Physica B: Condensed Matter",
title = "Phonon hardening due to the small-polaron effect",
volume = "355",
number = "1-4",
pages = "417-426",
doi = "10.1016/j.physb.2004.11.070"
}

Ivić, Z., Zeković, S., Čevizović, D.,& Kostić, D.. (2005). Phonon hardening due to the small-polaron effect. in Physica B: Condensed Matter, 355(1-4), 417-426.
https://doi.org/10.1016/j.physb.2004.11.070

Ivić Z, Zeković S, Čevizović D, Kostić D. Phonon hardening due to the small-polaron effect. in Physica B: Condensed Matter. 2005;355(1-4):417-426.
doi:10.1016/j.physb.2004.11.070 .

Ivić, Zoran, Zeković, Slobodan, Čevizović, Dalibor, Kostić, Dragan, "Phonon hardening due to the small-polaron effect" in Physica B: Condensed Matter, 355, no. 1-4 (2005):417-426,
https://doi.org/10.1016/j.physb.2004.11.070 . .

TY  - JOUR
AU  - Ivić, Zoran
AU  - Zeković, Slobodan
AU  - Kostić, Dragan
PY  - 2002
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2501
AB  - We report the results of theoretical examinations of large polaron motion in one-dimensional (1D) molecular crystals under the influence of thermal fluctuations of the host lattice and constant electric field. Such a situation may arise in biological macromolecules such as an alpha helix where charge (electron) transfer may be achieved by a polaron (soliton) mechanism. In that case, the electric field represents the effective endogenous electric field which is always present in realistic conditions. We derive and solve the Fokker-Planck equation for the distribution function of the solitons center-of-mass position. It is shown that the soliton effectively exhibits a random walk. Moreover, in order to examine statistical properties of the soliton wave function, we calculate the mean value of the soliton probability density: LT \beta(x,t)\(2) GT and we find that, for sufficiently large times, thermal fluctuations destruct the soliton, which transforms into the Gaussian packet. These results were used in order to estimate the relevance of the soliton model of charge transfer in polypeptide chains.
T2  - Physical Review E
T1  - Finite-temperature large acoustic polaron dynamics in quasi-one-dimensional molecular crystals
VL  - 65
IS  - 2
DO  - 10.1103/PhysRevE.65.021911
ER  - 

@article{
author = "Ivić, Zoran and Zeković, Slobodan and Kostić, Dragan",
year = "2002",
abstract = "We report the results of theoretical examinations of large polaron motion in one-dimensional (1D) molecular crystals under the influence of thermal fluctuations of the host lattice and constant electric field. Such a situation may arise in biological macromolecules such as an alpha helix where charge (electron) transfer may be achieved by a polaron (soliton) mechanism. In that case, the electric field represents the effective endogenous electric field which is always present in realistic conditions. We derive and solve the Fokker-Planck equation for the distribution function of the solitons center-of-mass position. It is shown that the soliton effectively exhibits a random walk. Moreover, in order to examine statistical properties of the soliton wave function, we calculate the mean value of the soliton probability density: LT \beta(x,t)\(2) GT and we find that, for sufficiently large times, thermal fluctuations destruct the soliton, which transforms into the Gaussian packet. These results were used in order to estimate the relevance of the soliton model of charge transfer in polypeptide chains.",
journal = "Physical Review E",
title = "Finite-temperature large acoustic polaron dynamics in quasi-one-dimensional molecular crystals",
volume = "65",
number = "2",
doi = "10.1103/PhysRevE.65.021911"
}

Ivić, Z., Zeković, S.,& Kostić, D.. (2002). Finite-temperature large acoustic polaron dynamics in quasi-one-dimensional molecular crystals. in Physical Review E, 65(2).
https://doi.org/10.1103/PhysRevE.65.021911

Ivić Z, Zeković S, Kostić D. Finite-temperature large acoustic polaron dynamics in quasi-one-dimensional molecular crystals. in Physical Review E. 2002;65(2).
doi:10.1103/PhysRevE.65.021911 .

Ivić, Zoran, Zeković, Slobodan, Kostić, Dragan, "Finite-temperature large acoustic polaron dynamics in quasi-one-dimensional molecular crystals" in Physical Review E, 65, no. 2 (2002),
https://doi.org/10.1103/PhysRevE.65.021911 . .

TY  - JOUR
AU  - Ivić, Zoran
AU  - Pržulj, Željko
AU  - Kostić, Dragan
PY  - 2000
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2352
AB  - Dynamics and the stability of the multivibron solitons in molecular chains have been examined by means of the perturbation method based upon the inverse scattering transform. We demonstrate that due to the coupling with phonons the soliton radiates energy which causes its slowing down and gradual decay of its amplitude. It was shown that the soliton lifetime depends strongly on temperature and the values of the basic physical parameters of the system. On the basis of these results the possible role of the multivibron solitons in the intramolecular vibrational energy transfer has been critically assessed.
T2  - Physical Review E
T1  - Decay and slowing down of the multiquanta Davydov-like solitons in molecular chains
VL  - 61
IS  - 6
SP  - 6963
EP  - 6970
DO  - 10.1103/PhysRevE.61.6963
ER  - 

@article{
author = "Ivić, Zoran and Pržulj, Željko and Kostić, Dragan",
year = "2000",
abstract = "Dynamics and the stability of the multivibron solitons in molecular chains have been examined by means of the perturbation method based upon the inverse scattering transform. We demonstrate that due to the coupling with phonons the soliton radiates energy which causes its slowing down and gradual decay of its amplitude. It was shown that the soliton lifetime depends strongly on temperature and the values of the basic physical parameters of the system. On the basis of these results the possible role of the multivibron solitons in the intramolecular vibrational energy transfer has been critically assessed.",
journal = "Physical Review E",
title = "Decay and slowing down of the multiquanta Davydov-like solitons in molecular chains",
volume = "61",
number = "6",
pages = "6963-6970",
doi = "10.1103/PhysRevE.61.6963"
}

Ivić, Z., Pržulj, Ž.,& Kostić, D.. (2000). Decay and slowing down of the multiquanta Davydov-like solitons in molecular chains. in Physical Review E, 61(6), 6963-6970.
https://doi.org/10.1103/PhysRevE.61.6963

Ivić Z, Pržulj Ž, Kostić D. Decay and slowing down of the multiquanta Davydov-like solitons in molecular chains. in Physical Review E. 2000;61(6):6963-6970.
doi:10.1103/PhysRevE.61.6963 .

Ivić, Zoran, Pržulj, Željko, Kostić, Dragan, "Decay and slowing down of the multiquanta Davydov-like solitons in molecular chains" in Physical Review E, 61, no. 6 (2000):6963-6970,
https://doi.org/10.1103/PhysRevE.61.6963 . .

TY  - JOUR
AU  - Ivić, Zoran
AU  - Tekić, Jasmina
AU  - Kostić, Dragan
PY  - 1998
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2182
AB  - Within the framework of the sine-Gordon model, the phenomenon of magnetoacoustic resonance has been analyzed. It was found that MAR arises on account of the common motion of magnetic and lattice solitons.
T2  - Solid State Phenomena
T1  - Theoretical examination of magneto-acoustic resonance within the framework of the sine-Gordon model
VL  - 61-2
SP  - 295
EP  - 299
DO  - 10.4028/www.scientific.net/ssp.61-62.295
UR  - https://hdl.handle.net/21.15107/rcub_vinar_2182
ER  - 

@article{
author = "Ivić, Zoran and Tekić, Jasmina and Kostić, Dragan",
year = "1998",
abstract = "Within the framework of the sine-Gordon model, the phenomenon of magnetoacoustic resonance has been analyzed. It was found that MAR arises on account of the common motion of magnetic and lattice solitons.",
journal = "Solid State Phenomena",
title = "Theoretical examination of magneto-acoustic resonance within the framework of the sine-Gordon model",
volume = "61-2",
pages = "295-299",
doi = "10.4028/www.scientific.net/ssp.61-62.295",
url = "https://hdl.handle.net/21.15107/rcub_vinar_2182"
}

Ivić, Z., Tekić, J.,& Kostić, D.. (1998). Theoretical examination of magneto-acoustic resonance within the framework of the sine-Gordon model. in Solid State Phenomena, 61-2, 295-299.
https://doi.org/10.4028/www.scientific.net/ssp.61-62.295
https://hdl.handle.net/21.15107/rcub_vinar_2182

Ivić Z, Tekić J, Kostić D. Theoretical examination of magneto-acoustic resonance within the framework of the sine-Gordon model. in Solid State Phenomena. 1998;61-2:295-299.
doi:10.4028/www.scientific.net/ssp.61-62.295
https://hdl.handle.net/21.15107/rcub_vinar_2182 .

Ivić, Zoran, Tekić, Jasmina, Kostić, Dragan, "Theoretical examination of magneto-acoustic resonance within the framework of the sine-Gordon model" in Solid State Phenomena, 61-2 (1998):295-299,
https://doi.org/10.4028/www.scientific.net/ssp.61-62.295 .,
https://hdl.handle.net/21.15107/rcub_vinar_2182 .

TY  - JOUR
AU  - Pržulj, Željko
AU  - Kostić, Dragan
AU  - Ivić, Zoran
PY  - 1998
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2181
AB  - The problem of the existence and stability of various types of self-trapped (ST) states (polarons) in 1-d molecular systems has been analysed within the framework of the general theory of self-trapping phenomena. An interpolation method is applied to cover the whole range of system parameters. In the system phase diagram we specify the areas where different ST states may exist. The role of the soliton mechanism in the energy and charge transport in biological systems has been critically revised on the basis of these results.
T2  - Solid State Phenomena
T1  - Classification and existence of polarons and solitons in molecular chains: Phase diagram
VL  - 61-2
SP  - 291
EP  - 294
DO  - 10.4028/www.scientific.net/ssp.61-62.291
UR  - https://hdl.handle.net/21.15107/rcub_vinar_2181
ER  - 

@article{
author = "Pržulj, Željko and Kostić, Dragan and Ivić, Zoran",
year = "1998",
abstract = "The problem of the existence and stability of various types of self-trapped (ST) states (polarons) in 1-d molecular systems has been analysed within the framework of the general theory of self-trapping phenomena. An interpolation method is applied to cover the whole range of system parameters. In the system phase diagram we specify the areas where different ST states may exist. The role of the soliton mechanism in the energy and charge transport in biological systems has been critically revised on the basis of these results.",
journal = "Solid State Phenomena",
title = "Classification and existence of polarons and solitons in molecular chains: Phase diagram",
volume = "61-2",
pages = "291-294",
doi = "10.4028/www.scientific.net/ssp.61-62.291",
url = "https://hdl.handle.net/21.15107/rcub_vinar_2181"
}

Pržulj, Ž., Kostić, D.,& Ivić, Z.. (1998). Classification and existence of polarons and solitons in molecular chains: Phase diagram. in Solid State Phenomena, 61-2, 291-294.
https://doi.org/10.4028/www.scientific.net/ssp.61-62.291
https://hdl.handle.net/21.15107/rcub_vinar_2181

Pržulj Ž, Kostić D, Ivić Z. Classification and existence of polarons and solitons in molecular chains: Phase diagram. in Solid State Phenomena. 1998;61-2:291-294.
doi:10.4028/www.scientific.net/ssp.61-62.291
https://hdl.handle.net/21.15107/rcub_vinar_2181 .

Pržulj, Željko, Kostić, Dragan, Ivić, Zoran, "Classification and existence of polarons and solitons in molecular chains: Phase diagram" in Solid State Phenomena, 61-2 (1998):291-294,
https://doi.org/10.4028/www.scientific.net/ssp.61-62.291 .,
https://hdl.handle.net/21.15107/rcub_vinar_2181 .

TY  - JOUR
AU  - Keković, Goran
AU  - Ivić, Zoran
AU  - Kostić, Dragan
PY  - 1998
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2109
AB  - The possible large-polaron contribution to the neutron scattering on quasi-one-dimensional molecular crystals was examined within the continuum polaron model. It was found that the appearance of the central peak in the dynamic structure factor should be expected if large-polaron formation takes place. The possibility of the experimental verification of the existence of Davydov-like solitons in biological systems was discussed on the basis of these predictions.
T2  - Europhysics Letters / EPL
T1  - On the neutron scattering on large polarons in quasi-one-dimensional molecular crystals
VL  - 41
IS  - 3
SP  - 285
EP  - 290
DO  - 10.1209/epl/i1998-00144-3
ER  - 

@article{
author = "Keković, Goran and Ivić, Zoran and Kostić, Dragan",
year = "1998",
abstract = "The possible large-polaron contribution to the neutron scattering on quasi-one-dimensional molecular crystals was examined within the continuum polaron model. It was found that the appearance of the central peak in the dynamic structure factor should be expected if large-polaron formation takes place. The possibility of the experimental verification of the existence of Davydov-like solitons in biological systems was discussed on the basis of these predictions.",
journal = "Europhysics Letters / EPL",
title = "On the neutron scattering on large polarons in quasi-one-dimensional molecular crystals",
volume = "41",
number = "3",
pages = "285-290",
doi = "10.1209/epl/i1998-00144-3"
}

Keković, G., Ivić, Z.,& Kostić, D.. (1998). On the neutron scattering on large polarons in quasi-one-dimensional molecular crystals. in Europhysics Letters / EPL, 41(3), 285-290.
https://doi.org/10.1209/epl/i1998-00144-3

Keković G, Ivić Z, Kostić D. On the neutron scattering on large polarons in quasi-one-dimensional molecular crystals. in Europhysics Letters / EPL. 1998;41(3):285-290.
doi:10.1209/epl/i1998-00144-3 .

Keković, Goran, Ivić, Zoran, Kostić, Dragan, "On the neutron scattering on large polarons in quasi-one-dimensional molecular crystals" in Europhysics Letters / EPL, 41, no. 3 (1998):285-290,
https://doi.org/10.1209/epl/i1998-00144-3 . .

TY  - JOUR
AU  - Ivić, Zoran
AU  - Kostić, Dragan
AU  - Pržulj, Željko
AU  - Kapor, Darko
PY  - 1997
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2053
AB  - The dressing effect due to the quantum nature of phonons may cause the creation of bound states of several vibrons in the molecular chain. The possibility of creating soliton states of this type is discussed for the simple Frohlich one-dimensional model. The regions of the system parameter space where different mechanisms dominate the behaviour of such entities are characterized.
T2  - Journal of Physics: Condensed Matter
T1  - Effects of quantum lattice fluctuations on multiquanta Davydov-like solitons in a molecular chain
VL  - 9
IS  - 2
SP  - 413
EP  - 426
DO  - 10.1088/0953-8984/9/2/010
ER  - 

@article{
author = "Ivić, Zoran and Kostić, Dragan and Pržulj, Željko and Kapor, Darko",
year = "1997",
abstract = "The dressing effect due to the quantum nature of phonons may cause the creation of bound states of several vibrons in the molecular chain. The possibility of creating soliton states of this type is discussed for the simple Frohlich one-dimensional model. The regions of the system parameter space where different mechanisms dominate the behaviour of such entities are characterized.",
journal = "Journal of Physics: Condensed Matter",
title = "Effects of quantum lattice fluctuations on multiquanta Davydov-like solitons in a molecular chain",
volume = "9",
number = "2",
pages = "413-426",
doi = "10.1088/0953-8984/9/2/010"
}

Ivić, Z., Kostić, D., Pržulj, Ž.,& Kapor, D.. (1997). Effects of quantum lattice fluctuations on multiquanta Davydov-like solitons in a molecular chain. in Journal of Physics: Condensed Matter, 9(2), 413-426.
https://doi.org/10.1088/0953-8984/9/2/010

Ivić Z, Kostić D, Pržulj Ž, Kapor D. Effects of quantum lattice fluctuations on multiquanta Davydov-like solitons in a molecular chain. in Journal of Physics: Condensed Matter. 1997;9(2):413-426.
doi:10.1088/0953-8984/9/2/010 .

Ivić, Zoran, Kostić, Dragan, Pržulj, Željko, Kapor, Darko, "Effects of quantum lattice fluctuations on multiquanta Davydov-like solitons in a molecular chain" in Journal of Physics: Condensed Matter, 9, no. 2 (1997):413-426,
https://doi.org/10.1088/0953-8984/9/2/010 . .

TY  - JOUR
AU  - Stošić, Borko D.
AU  - Sastry, Srikanth
AU  - Kostić, Dragan
AU  - Milošević, Sava
AU  - Stanley, Eugene H.
PY  - 1996
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2017
AB  - We describe a geometric approach for studying phase transitions, based upon the analysis of the density of states (DOS) functions (exact partition functions) for finite Ising systems. This approach presents a complementary method to the standard Monte Carlo method, since with a single calculation of the density of states (which is independent of parameters and depends only on the topology of the system), the entire range of parameter values can be studied with minimal additional effort. We calculate the DOS functions for the nearest-neighbor (nn) Ising model in nonzero field for square lattices up to 12 x 12 spins, and for triangular lattices up to 12 spins in the base; this work significantly extends previous exact calculations of the partition function in nonzero field (8 x 8 spins for the square lattice). To recognize features of the DOS functions that correspond to phase transitions, we compare them with the DOS functions for the Ising chain and for the Ising model defined on a Sierpinski gasket. The DOS functions define a surface with respect to the dimensionless independent energy and magnetization variables; this surface is convex with respect to magnetization in the low-energy region for systems displaying a second-order phase transition. On the other hand, for systems for which there is no phase transition, the DOS surfaces are concave. We show that this geometrical property of the DOS functions is generally related to the existence of phase transitions, thereby providing a graphic tool for exploring various features of phase transitions. For each given temperature and field, we also define a free energy surface, from which we obtain the most probable energy and magnetization. We test this method of free energy surfaces on Ising systems with both nearest-neighbor (J(1)) and next-nearest-neighbor (J(2)) interactions for various values of the ratio R = J(1)/J(2). For one particular choice, R = -0.1, we show how the free energy surface may be utilized to discern a first-order phase transition. We also carry out Monte Carlo simulations and compare these quantitatively with our results for the phase diagram.
T2  - Physica A: Statistical Mechanics and Its Applications
T1  - Geometric criteria for phase transitions: The Ising model with nearest and next-nearest neighbor interactions
VL  - 232
IS  - 1-2
SP  - 349
EP  - 368
DO  - 10.1016/0378-4371(96)00239-7
UR  - https://hdl.handle.net/21.15107/rcub_vinar_2017
ER  - 

@article{
author = "Stošić, Borko D. and Sastry, Srikanth and Kostić, Dragan and Milošević, Sava and Stanley, Eugene H.",
year = "1996",
abstract = "We describe a geometric approach for studying phase transitions, based upon the analysis of the density of states (DOS) functions (exact partition functions) for finite Ising systems. This approach presents a complementary method to the standard Monte Carlo method, since with a single calculation of the density of states (which is independent of parameters and depends only on the topology of the system), the entire range of parameter values can be studied with minimal additional effort. We calculate the DOS functions for the nearest-neighbor (nn) Ising model in nonzero field for square lattices up to 12 x 12 spins, and for triangular lattices up to 12 spins in the base; this work significantly extends previous exact calculations of the partition function in nonzero field (8 x 8 spins for the square lattice). To recognize features of the DOS functions that correspond to phase transitions, we compare them with the DOS functions for the Ising chain and for the Ising model defined on a Sierpinski gasket. The DOS functions define a surface with respect to the dimensionless independent energy and magnetization variables; this surface is convex with respect to magnetization in the low-energy region for systems displaying a second-order phase transition. On the other hand, for systems for which there is no phase transition, the DOS surfaces are concave. We show that this geometrical property of the DOS functions is generally related to the existence of phase transitions, thereby providing a graphic tool for exploring various features of phase transitions. For each given temperature and field, we also define a free energy surface, from which we obtain the most probable energy and magnetization. We test this method of free energy surfaces on Ising systems with both nearest-neighbor (J(1)) and next-nearest-neighbor (J(2)) interactions for various values of the ratio R = J(1)/J(2). For one particular choice, R = -0.1, we show how the free energy surface may be utilized to discern a first-order phase transition. We also carry out Monte Carlo simulations and compare these quantitatively with our results for the phase diagram.",
journal = "Physica A: Statistical Mechanics and Its Applications",
title = "Geometric criteria for phase transitions: The Ising model with nearest and next-nearest neighbor interactions",
volume = "232",
number = "1-2",
pages = "349-368",
doi = "10.1016/0378-4371(96)00239-7",
url = "https://hdl.handle.net/21.15107/rcub_vinar_2017"
}

Stošić, B. D., Sastry, S., Kostić, D., Milošević, S.,& Stanley, E. H.. (1996). Geometric criteria for phase transitions: The Ising model with nearest and next-nearest neighbor interactions. in Physica A: Statistical Mechanics and Its Applications, 232(1-2), 349-368.
https://doi.org/10.1016/0378-4371(96)00239-7
https://hdl.handle.net/21.15107/rcub_vinar_2017

Stošić BD, Sastry S, Kostić D, Milošević S, Stanley EH. Geometric criteria for phase transitions: The Ising model with nearest and next-nearest neighbor interactions. in Physica A: Statistical Mechanics and Its Applications. 1996;232(1-2):349-368.
doi:10.1016/0378-4371(96)00239-7
https://hdl.handle.net/21.15107/rcub_vinar_2017 .

Stošić, Borko D., Sastry, Srikanth, Kostić, Dragan, Milošević, Sava, Stanley, Eugene H., "Geometric criteria for phase transitions: The Ising model with nearest and next-nearest neighbor interactions" in Physica A: Statistical Mechanics and Its Applications, 232, no. 1-2 (1996):349-368,
https://doi.org/10.1016/0378-4371(96)00239-7 .,
https://hdl.handle.net/21.15107/rcub_vinar_2017 .

TY  - JOUR
AU  - Ivić, Zoran
AU  - Tsironis, Giorgos P.
AU  - Kostić, Dragan
AU  - Lalić, Milan V.
PY  - 1996
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1957
AB  - We study small-polaron self-trapping properties in the two-state molecular crystal model by employing a finite-temperature variational non-adiabatic approach that is an extension to the semiclassical adiabatic Pekar theory. We find two distinct regions in the space of coupling constant versus adiabaticity parameter that are separated by a temperature-dependent critical line. In these regions the response of the lattice to the motion of the particle is quite different. We find conditions that allow for the determination of the character of the motion and the localization transition as a function of the physical parameters of the system and temperature.
T2  - Journal of Physics: Condensed Matter
T1  - Finite-temperature two-state small-polaron dynamics: Averaged Hamiltonian approach
VL  - 8
IS  - 2
SP  - 157
EP  - 167
DO  - 10.1088/0953-8984/8/2/005
ER  - 

@article{
author = "Ivić, Zoran and Tsironis, Giorgos P. and Kostić, Dragan and Lalić, Milan V.",
year = "1996",
abstract = "We study small-polaron self-trapping properties in the two-state molecular crystal model by employing a finite-temperature variational non-adiabatic approach that is an extension to the semiclassical adiabatic Pekar theory. We find two distinct regions in the space of coupling constant versus adiabaticity parameter that are separated by a temperature-dependent critical line. In these regions the response of the lattice to the motion of the particle is quite different. We find conditions that allow for the determination of the character of the motion and the localization transition as a function of the physical parameters of the system and temperature.",
journal = "Journal of Physics: Condensed Matter",
title = "Finite-temperature two-state small-polaron dynamics: Averaged Hamiltonian approach",
volume = "8",
number = "2",
pages = "157-167",
doi = "10.1088/0953-8984/8/2/005"
}

Ivić, Z., Tsironis, G. P., Kostić, D.,& Lalić, M. V.. (1996). Finite-temperature two-state small-polaron dynamics: Averaged Hamiltonian approach. in Journal of Physics: Condensed Matter, 8(2), 157-167.
https://doi.org/10.1088/0953-8984/8/2/005

Ivić Z, Tsironis GP, Kostić D, Lalić MV. Finite-temperature two-state small-polaron dynamics: Averaged Hamiltonian approach. in Journal of Physics: Condensed Matter. 1996;8(2):157-167.
doi:10.1088/0953-8984/8/2/005 .

Ivić, Zoran, Tsironis, Giorgos P., Kostić, Dragan, Lalić, Milan V., "Finite-temperature two-state small-polaron dynamics: Averaged Hamiltonian approach" in Journal of Physics: Condensed Matter, 8, no. 2 (1996):157-167,
https://doi.org/10.1088/0953-8984/8/2/005 . .

TY  - JOUR
AU  - Ivić, Zoran
AU  - Pržulj, Željko
AU  - Kostić, Dragan
AU  - Kapor, Darko
AU  - Škrinjar, Mario J.
PY  - 1996
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2007
AB  - The existence of a two-vibron (amide-I quanta) bound state has been examined within the framework of a two-site realization of the Davydov model. The parameter space of the system is divided into two regions where the nature of pairing and the character of bound states are determined by the quite different physical mechanisms, The validity of the semiclassical approximation was discussed.
T2  - Physical Review B: Condensed Matter and Materials Physics
T1  - Effects of quantum lattice fluctuations on vibron pairing in two-site systems
VL  - 54
IS  - 5
SP  - 2992
EP  - 2995
DO  - 10.1103/PhysRevB.54.2992
ER  - 

@article{
author = "Ivić, Zoran and Pržulj, Željko and Kostić, Dragan and Kapor, Darko and Škrinjar, Mario J.",
year = "1996",
abstract = "The existence of a two-vibron (amide-I quanta) bound state has been examined within the framework of a two-site realization of the Davydov model. The parameter space of the system is divided into two regions where the nature of pairing and the character of bound states are determined by the quite different physical mechanisms, The validity of the semiclassical approximation was discussed.",
journal = "Physical Review B: Condensed Matter and Materials Physics",
title = "Effects of quantum lattice fluctuations on vibron pairing in two-site systems",
volume = "54",
number = "5",
pages = "2992-2995",
doi = "10.1103/PhysRevB.54.2992"
}

Ivić, Z., Pržulj, Ž., Kostić, D., Kapor, D.,& Škrinjar, M. J.. (1996). Effects of quantum lattice fluctuations on vibron pairing in two-site systems. in Physical Review B: Condensed Matter and Materials Physics, 54(5), 2992-2995.
https://doi.org/10.1103/PhysRevB.54.2992

Ivić Z, Pržulj Ž, Kostić D, Kapor D, Škrinjar MJ. Effects of quantum lattice fluctuations on vibron pairing in two-site systems. in Physical Review B: Condensed Matter and Materials Physics. 1996;54(5):2992-2995.
doi:10.1103/PhysRevB.54.2992 .

Ivić, Zoran, Pržulj, Željko, Kostić, Dragan, Kapor, Darko, Škrinjar, Mario J., "Effects of quantum lattice fluctuations on vibron pairing in two-site systems" in Physical Review B: Condensed Matter and Materials Physics, 54, no. 5 (1996):2992-2995,
https://doi.org/10.1103/PhysRevB.54.2992 . .