朱邦芬只保留电子-声子互作用算符 对角项，把非对角项作为微扰处理；

原则上，不同的电子态对应于不同的晶格平衡位置；通常计算固体的振动性质时，假定电子处于基态。

-Zhu bonfim retain only electronic- phonon interaction diagonal operator, the diagonal of the non-perturbative as processing　in principle, different electronic states corresponding to different lattice equilibrium position　usually calculate the vibration of the solid nature, it is assumed that e in the ground state.