Abstract

A one-dimensional nonlinear dynamical system of coupled intra-site excitations and lattice vibrations is studied. The system as a whole is shown to be integrable in the Lax sense and it admits the exact four-component analytical solution demonstrating the pronounced mutual influence between the interacting subsystems in the form of essentially nonlinear superposition of two principally distinct types of traveling waves. The inter-play between the coupling strength and the parameter of localization causes the criticality of system’s dynamics manifested as the dipole-monopole transition in the spatial distribution of intra-site excitations.

Key words: exciton-phonon coupling, nonlinear integrable system, one-dimensional lattice, nonlinear wave packet, dipole-monopole transition.