POLARONS ON A ONE-DIMENSIONAL NONLINEAR LATTICE WITH 2 STRUCTURAL PHASES

The case of polaron and bipolaron formation due to electron-phonon cou pling was studied on a lattice with soft non-linear intersite interact ions. The ground state of a system that consists of one or two electro ns coupled to a non-linear lattice was obtained numerically. The bindi ng energy of the bipolaron was examined as a function of the degree of the non-linearity of the lattice. A model was investigated where the interatomic interactions in the lattice are described by a double-well potential. This type of non-linear interaction strongly influences th e bipolaron formation and generally improves its stability and increas es its binding energy by permitting a local structural change of the l attice.