中文摘要：

采用密度泛函理论（DFT）中的广义梯度近似（GGA）对MomSn（m＋n≤8）团簇进行结构优化,通过计算其二阶能量差分Δ2Em、分裂能D（m）、平均结合能Eb、最高占据轨道（HOMO）、最低空轨道（LUMO）和HOMO-LUMO能隙HLG,以表征与分析团簇总原子数对MomSn团簇基态结构稳定性的影响。计算结果表明：随着总原子数（m＋n）的增大,MomSn团簇的基态结构由较为松散的平面结构向紧凑型的空间结构转变,其基态几何构型与Sn团簇以及Mom团簇的基态几何构型密切相关;MomSn团簇结构稳定性随团簇原子总数（m＋n）的增加而增大,MomSn团簇的平均结合能比Sn团簇和Mom团簇的平均结合能要大;Mo Sn团簇、Mo2Sn团簇、Mo3Sn团簇的幻数（n）分别为5、4、3;在MomSn团簇中,电荷均是由Mo原子向S原子转移的,并以共价键和离子键共存。

英文摘要：

The geometries of the Mo_mS_n（m＋n≤8） clusters were optimized using density functional theory（DFT） with generalized gradient approximation（GGA） for exchange-correlation functional. Several parameters, such as the second difference of energies（Δ2Em）, the fission energy（D（m））, average binding energy（Eb）, highest occupied molecular orbital（HOMO）, lowest unoccupied molecular orbital（LUMO） and the HOMO-LUMO energy gap（HLG）, were calculated to characterize and analyze the influence of total atom number on the structural stabilities of MomSn clusters. The calculated results show that the ground state structures change from incompact planar structures to closed-packed structures with the increase of total atom number （m＋n）, the ground state structures are mainly based on the ground state structures of Sn clusters and Morn clusters. And the structural stabilities of MomSn clusters increase with the increase of total atom number, and the average binding energy Of MomSn clusters is higher than those of S, clusters and Morn clusters. when the magic numbers （n） of MoSn clusters, Mo2Sn clusters and Mo3Sn clusters are 5, 4, and 3, respectively, the charge transfers from Mo atom to S atom in MomSn clusters and the co-existence of covalent and ionic bond can be found.