Study on Two Generalized FK Models**The project supported by National Natural Science Foundation of China and Science Foundation of China Academy of Engineering Physics

Abstract

We study two generalized FK models. Each describes a chain of atoms connected by double-well interactions in the presence of a perturbed sinusoidal external potential. The phase diagram varies with the period of the external potential D and with the amplitude of the perturbation ε. Some novel and complex phase structures are found. There are two threshold values of D for each model, which equal the distance and two times of the distance between the two wells of the interatomic interactions, respectively. Within different interval of D, the phase diagrams exhibit different behaviors.