密度泛函方法研究NiSin(n=1～13)团簇

A density functional theory investigation of NiSi_n(n=1～13)clusters

基于第一性原理，利用密度泛函理论中的广义梯度近似（GGA）系统研究了NiSin（n=1～13）团簇，在充分考虑自旋多重度的基础上讨论了这些团簇的生长行为，电子性质及其磁性．结果表明：NiSin＋1的基态结构是在NiSin的基态结构上带帽一个Si原子而得到；随着团簇尺寸的增大，Ni原子逐渐从吸附在Sin团簇的表面位置移动到Sin团簇笼内；掺杂Ni原子提高了硅团簇的稳定性；NiSi10团簇的稳定性在所有团簇中是最高的；电子总是从Si向Ni转移，Ni原子所带的电荷数不仅与Ni原子的配位数有关，还与NiSin团簇的基态结构密切相关；当n=1～2时，团簇的自旋总磁矩为2μB，当n≥3时，团簇的磁性消失，这可能与Ni原子内部较强的sp-d杂化以及Si原子内部的s-p杂化有关．

Based on the first principles, NiSin （ n = 1 - 13） clusters have been systematically investigated by using the density functional theory with the generalized gradient approximation. The growth patterns, electronic properties and magnetism of NiSin clusters with different spin multiplicities are discussed in detail. The calculated results indicate that the stable NiSin ＋ 1 geometries are generated with one Si atom being face capped on the stable NiSin clusters;Ni atom gradually moves from the surface-absorbed site to the concave site of the silicon cage with increasing size of NiSin clusters;the doping of Ni atom can enhance the stability of the Sin clusters;the NiSi10 cluster is the most stable specie of all different-sized clusters; charges always transfer from Si atoms to Ni atom in all-sized NiSin clusters,charges of Ni atom are relation to not only coordination numbers of Ni atom but also the ground state structure of NiSin clusters;the total spin magnetic moment of NiSin cluster is about 2μB at n = 1,2,and the spin magnetic moment of NiSin cluster is quenched when n surpasses 2, the strong hybridization between Ni 3d, 4s, 4p and Si 3s, 3p states might be one major reason for quenching the magnetic moment of NiSin cluster.