Dynamics of solitary waves in diatomic chains with long-range Kac-Baker interactions

Abstract

An analytical study of the influence of the long-range atomic interactions on the properties of soliton-like excitations in a one-dimensional (1D) anharmonic chain is presented. The model chosen is a nonlinear diatomic chain in which atoms are assumed to interact via a cubic and/or quartic nonlinear short-range potential and a linear long-range Kac-Baker type pair potential. In the continuum approximation, using scaling arguments, it is shown that the coupled nonlinear difference-differential equations for the motion of the two different masses can be decoupled and reduced to a generalized Boussinesq equation which admits supersonic and subsonic acoustic kink (pulse) solitons, long-wavelength acoustic oscillating solutions of breather type and optical envelope type solitons of a nonlinear Schrodinger equation. A possible alternation of envelope and dark is found that can exist not only for acoustic mode but also for optical mode.