Biphonons in the beta-Fermi-Pasta-Ulam model
Discrete breathers or intrinsic localized modes are nonlinear localized states that appear in several classical extended systems, such as for instance the Fermi-Paste-Ulam (FPU) model. In order to probe the quantum states that correspond to discrete breathers, we quantize the beta-FPU model using boson quantization rules, retain only number conserving terms, and analyze the two-quanta sector of the model. For both attractive and repulsive nonlinearity, we find the occurrence of biphonons in two forms, on-site and nearest-neighbor site, and analyze their properties. We comment on the use of this model as a minimal model for extended molecular and biomolecular systems. (c) 2006 Elsevier B.V. All rights reserved.
Keywords:Fermi-Pasta-Ulam model / discrete breathers / quantum breathers / biphonons
Source:Physica. D: Nonlinear Phenomena, 2006, 216, 1, 200-206
- Conference on Nonlinear Physics - Condensed Matter, Dynamical Systems and Biophysics, May 30-31, 2005, Inst Henri Poincare, Paris, France