极化子在正弦色散声子场中的性质

Properties of Polaron in a Sine Dispersion Phonon Field

本文计及纵光学声子的色散 ,在正弦近似下 ,用微扰法计算了多原子晶体中极化子的基态能量 。

With the development of matter science and technology, the properties of polaron in crystals have been of considerable interest. Many investigators studied the polaron problem by means of various theoretical methods. There are many references and remarkable works. In most polar crystals there is one mode of the longitudinal optical(LO) phonon. The properties of crystals have been studied by a great variety of techniques in the case of the crystals having only one LO phonon branch. However, a large number of polar crystals, with several atoms per unit cell, have more than one LO phonon branch. For example, a large number of perovskites and quaternary compound semiconductor crystals have more than two LO phonon branches. In recent years, the polaron problem with many LO phonon branches has been investigated. Hu and Xiao et al. have discussed the properties of the polaron and exciton in polyatomic polar crystals using a linear combination operator method. Frequency of the lattice vibration in ionic crystals bears a relation to the wave vector. In general case,when treating the interaction between the longitudinal optical vibration in ionic crystals and charged particle, the frequency of the phonon is always thought to be constant, and the variation of this frequency with the wave vector is neglected. Gu discussed the influence of the dispersion of LO phonon on the properties of polaron under considering the dispersion of LO phonon for the first time. In this paper, the dispersion of the longitudinal optical phonons is considered in a sine approximation. The ground state energy, effective mass and self energy of a polaron in polyatomic crystals are calculated using perturbation method.