中文摘要：

采用基于密度泛函理论的第一性原理赝势平面波方法，对闪锌矿结构CdS和CdS：M（M=Ti，Co）几何结构、电荷分布、能带结构和电子态密度等进行了系统研究．几何结构研究对晶格参量进行了优化计算，Co和Ti原子掺入CdS后晶格常数均减小，晶格发生局部畸变．电荷密度计算表明，对于掺Co体系，近邻的S原子电荷分布变化明显，即有更多电子转移到S原子，同时次近邻Cd原子周围的电子分布也受到影响；对于Ti体系，邻近S原子电荷分布变化不明显，次近邻Cd原子周围电荷也没有重新分布．能带结构和态密度分析表明，由于Co3d和Ti3d电子的引入，CdS：Co成为铁磁半导体，而CdS：Ti为简并半导体．

英文摘要：

The structure and electronic properties of zinc blende CdS and CdS ： M（M= Co,Ti） are studied from DFT based first-principles pseudopotential calculations. It shows that the M doped material have a smaller lattice constant, which results in a local lattice distortion. The charge density is calculated and differences between the pure and doped materials are compared. Results reveal that for the Co doped material,more electrons will be transferred from Co atom to the surrounding S atoms, and the transferred charge finally influences the charge redistribution of the Cd atoms that connected with the S atoms in other directions. For the non-magnetic metal Ti doped cases, the doped Ti atom changed a little the charge distribution around the surrounding S atoms, and charge distribution around the Cd atom is almost the same as the undoped case. The band structure and density of states （DOS） are calculated,which show that CdS： Co is ferromagnetic semiconductor while CdS ： Ti is degenerate semiconductor due to the introduction of Co 3d and Ti 4d.