Ca_2Si_n(n=1～9)团簇结构、稳定性与光谱性质的理论研究  

Theoretical Study of the Structural,Stability and Spectral Properties of Ca_2Si_n(n=1～9)Clusters

作　　者：张帅[1] 张颖颖[1] 张萍[1] 李根全[1] 吕林霞[1] 卢成[1] 

机构地区：[1]南阳师范学院物理与电子工程学院,河南南阳473061

出　　处：《光学学报》2013年第11期172-178,共7页Acta Optica Sinica

基　　金：国家自然科学基金(10947020);河南省自然科学基金(2011B140015);河南省青年骨干教师基金(2012GGJS-152)

摘　　要：采用密度泛函理论（DFT）中的杂化密度泛函B3LYP方法，在6-311G （d）基组的水平上研究了Ca2Sin（n=1~9）团簇的平衡几何结构、稳定性与光谱性质。结构优化表明：Ca2Sin团簇的基态绝大多数为立体结构（除了n=1，2）。在获得的最低能量结构基础上计算并分析了掺杂团簇的平均结合能、二阶能量差分、分裂能、能隙与光谱性质与团簇尺寸的变化关系，计算结果发现：Ca原子的掺入使得体系的化学稳定性降低，Ca2Si5，Ca2Si7与Ca2Si9是幻数结构。从光谱性质分析来看，Ca2Si5团簇与Ca2Si9团簇的红外较强吸收峰的个数较多，而Ca2Si7团簇的红外较强吸收峰的个数则较少；Ca2Si5团簇的拉曼只有一个较强峰值且位于低频段内，Ca2Si7团簇与Ca2Si9团簇的拉曼较强峰的个数较多。The geometries, stabilities, and spectral properties of Ca2Sin（n=1~9） clusters are systematically investigated by using first principles calculations based on the hybrid density functional theory at the B3LYP / 6-311G （d） level. The optimized geometries indicate that the most stable structures of Ca2Sin clusters are three-dimensional structures for n=3~9. On the basis of the obtained lowest-energy geometries, the size dependence of cluster properties, such as averaged binding energies, second-order energy differences, fragmentation energies, HOMO-LUMO gaps and spectral properties, are discussed. The calculated results show that the impurity Ca atoms in the Ca2Sin clusters enhance the chemical stability of the silicon framework. The magic clusters are found at n=5, 7 and 9. In addition, the spectral analysis indicates, the number of the infrared （IR） absorption peaks of Ca2Si5 and Ca2Si9 is more, but Ca2Si7 is less. The Raman absorption peak of Ca2Si5 is only one and appears in the low frequency band, on the contray, Ca2Si7 and Ca2Si9 have more Raman absorption peaks.

关 键 词：光谱学 Ca2Sin(n=1~9)团簇 结构与稳定性 密度泛函理论 

分 类 号：O641[理学—物理化学]