The structure and magnetic properties of Osn （n=11～22） clusters are systematically studied by using density functional theory （DFT）. For each size, the average binding energy per atom, the second-order differences of total energies and the highest occupied molecular orbital （HOMO）–the lowest unoccupied molecular orbital （LUMO） gaps are calculated to analyze the stability of the cluster. The structures of Os14 and Os18 clusters are based on a close-packed hexagonal structure, and they have maximum stabilities, so n=14, 18 are the magic numbers. The 5d electrons play a dominant role in the chemical reaction of Osn clusters. The magnetic moments of Osn clusters are quenched around n=12, and when n=18～22 the value approximates to zero, due to the difference of electron transfer.
采用密度泛函理论中的B3LYP方法,在LANL2DZ基组水平上优化了WmBn(m+n≤7)团簇的几何结构,得到了它们的基态构型,并对其自然键轨道(natural bond orbital,NBO)以及振动光谱进行了计算研究.结果表明:团簇中NBO电荷分布状况与团簇的对称性相关;W原子比B原子电荷调节能力强,易与其他原子形成化学键;最大频率以及最强峰值对应的振动模式大部分是B原子或W原子的伸缩振动以及摇摆振动.
WnC0＇± （n= 1-6） clusters are investigated by using the density functional theory （DFT） at the B3LYP/LANL2DZ level. We find that the neutral, anionic and cationic ground state structures are similar within the same size, and constituted by substituting a C atom for one W atom in the structures of Wn＋1 clusters. The natural bond orbital （NBO） charge analyses indicate that the direction of electron transfer is from the W atom to the 2p orbital of the C atom. In addition, the calculated infrared spectra of the WnC0＇± （n= 2-6） clusters manifest that the vibrational frequencies of neutral, anionic and cationic clusters are similar in a range of 80 cm-1-864 cm-1. The high frequency, strong peak modes are found to be an almost stretched deformation of the carbide atom. Finally, the polarizabilities of WnC0＇± （n= 1-6） clusters are also discussed.
采用密度泛函理论(DFT)中的B3LYP方法,在LANL2DZ基组水平上优化W m B n(m+n≤7)团簇的几何结构,得到它们的基态构型,并对基态构型的平均结合能、二阶能量差分、能隙及WIB键级进行计算.结果表明:WB n团簇的基态构型均是平面结构;当m≥2且m+n≥4时,除W3B团簇外,其余团簇的基态结构均为立体结构;团簇的热力学稳定性随W原子个数的增加越来越好,W-W键的强度明显高于W-B和B-B键,W原子对团簇的稳定性起主导作用;W2B2和W3B团簇最稳定.
