In solution of the dynamical equation of a one-dimensional diatomic lattice, the dispersion law is obtained under the harmonic approximation, and the frequency of "optical" branch at the center of Brillioun zone is changed with on-site potential.The oscillation images are analyzed. In the case of long wavelength "optical" modes, the amplitudes of the two atoms within each cell are not identical. The long wavelength "optical" modes are different from the one of zero on-site potential.%在简谐近似下,求解具有在位势的一维双原子链晶格动力学方程,得出并分析新的色散关系.讨论了具有在位势的一维双原子链晶格振动的高频支长波模振动图像.
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