Solitons in a diatomic chain with competing nonlinearities

A one-dimensional diatomic chain whose energy contains cubic and quartic te rms in the atomic displacements is considered. A modified asymptotic method is proposed for finding soliton solutions to equations describing systems with nonlinearities of various symmetry. It is shown that the dynamics of t he model in question can be described in terms of equations that are simila r to the dynamic equations for a diatomic chain with an even potential func tion. Soliton solutions of a new, unusual type are found in the specific ca se of a free diatomic chain with a purely cubic anharmonic potential. (C) 2 001 MAIK "Nauka/Interperiodica".