中文摘要：

运用基于密度泛函理论DFT（density functional theory）的第一性原理方法,计算了黄铁矿、白铁矿和磁黄铁矿晶体的Mulliken布居、电荷密度、差分电荷密度及前线轨道,并进行了分析。计算结果表明,黄铁矿和白铁矿晶体的铁原子带负电,硫原子带正电,铁—硫键之间主要以共价性为主,另外,黄铁矿硫—硫键之间的共价性强于白铁矿;而磁黄铁矿晶体的铁原子带正电,硫原子带负电,两个铁原子之间形成Fe—Fe键,呈现出离子性。前线轨道研究表明,在黄铁矿和白铁矿晶体中,铁原子对最高占据分子轨道（HOMO）的贡献比硫原子的大,但对最低空轨道（LUMO）的贡献却比硫原子的小;而在磁黄铁矿晶体中铁原子和硫原子对前线轨道的贡献相近。研究结果有助于进一步了解不同晶体结构的硫铁矿的性质,对硫铁矿在实际中的应用具有理论指导意义。

英文摘要：

The Mulliken populations,electron density,electron density difference and frontier orbital of pyrite,marcasite and pyrrhotite crystals were calculated using the first principle method based on density functional theory（DFT）,and further analyzed in details.The calculation results revealed that the Fe atoms carry negative charge and S atoms carry positive charge of pyrite and marcasite crystals,with their Fe—S bonds mainly covalent.In addition,the covalency between S—S bonds of pyrite is stronger than that of marcasite.While the Fe atoms carry positive charge and S atoms carry negative charge of pyrrhotite crystal,between two Fe atoms formed Fe—Fe bond,showing ionic.The study of the frontier orbital indicated that Fe atoms exhibit larger contributions to the Highest Occupied Molecular Orbital（HOMO） than S atoms,but smaller contributions to the Lowest Unoccupied Molecular Orbital（LUMO） than S atoms in the pyrite and marcasite crystals.However,both Fe atoms and S atoms have similar contributions to the frontier orbital in the pyrrhotite crystal.The results presented here contribute to the understanding of different crystal structures of sulfurous iron minerals,and can be used in guiding related practical applications.