中文摘要：

使用基于局域密度近似的密度泛函方法，对立方相和六方相CdS的结构进行了模拟计算。结果表明：2种晶相的CdS不仅禁带宽度非常相近，两者相差8．51％，而且导带边都是由CdSs轨道贡献，价带边都是由S3p轨道贡献。这种相似的能带结构导致立方相和六方相CdS在可见光波段具有相近的光学性能，从而解释了实验获得的两相混合CdS仍然能够具有较好光学性能的现象。

英文摘要：

Theoretic investigation on cubic and hexagonal structures of CdS was done by a method of density function within the local density approximation. The study of the band structure and the density of states show that the band-gaps of cubic and hexagonal CdS are very close, which have a difference of less than 8.51%. The bottom of conduction-band and the top of valence-band of both phases are attributed to Cd5s and S3p orbits, respectively. The analysis of band structure implied that the two structures of CdS have a conformed optical property under visible spectrum, which also explains why the mixed structures of CdS still have good optical properties.