关键词: 二维正方晶格, 最紧邻, 频率色散

Abstract: based on the two -dimensional square lattice for example，we analyze the relations of the closest atom approximate dispersion，which is based on the discussion about the dispersion relation of one-dimensional lattice and lattice heat capacity. The numerical result has been presented by Matlab.

Key words: two-dimensional square lattice, closest atom, frequency dispersion