幻数铵离子水团簇NH4^＋（H20）20的结构和振动谱研究

采用Hartree—Fock方法和6—31G（d）基组对由经验势得到的幻数铵离子水团簇NH4^=（H20）20的17稳定构型进行了结构优化和频率计算，然后对优化所得结构在B3LYP／6—311＋＋G（d，p）水平上计算了单点能．通过比较结合能，笔者发现NH4^＋离子位于团簇中心的结构比其位于表面时更加稳定，两种结构能量的差值在1—5kcal／mol范围内．同时红外谱计算表明，中心结构与表面结构相比，伸缩振动区域较窄，并且最强振动峰发生了红移．

STRUCTURE AND INFRARED SPECTROSCOPY OF NH4 ^＋ （H2O） 20 CLUSTERS

Optimization and frequency calculations of candidate structures of magic number protonated ammonia water cluster NH4 ^＋ （H20） 20, which obtained from an empirical potential, are carried out with the Hartree -Fock methods and 6 -31G（d） basis set. 17 stable structures with different geometrical types are obtained. Single point energies are calculated at the DFT level with the B3LYP hybrid functional and the 6 -311 ＋ ＋ G（ d, p） basis set. By the comparision of bound energies, we find that the core structures are more stable than the facial structures, and the energy difference are in 1 -5kcal/mol.