平面五元水分子簇的量子化学研究

选用Gaussian03的B3LYP/6-31G(d,p)、DMol3的BLYP/DNP和deMon的BLYP/TZVP等方法计算了甲烷水合物(结构-1)中平面五元水分子簇的结合能和氢键能,作了基组重叠误差(BSSE)和色散能(dispersion)的修正,估算了次级相互作用的贡献.在DMol3程序中使用了大型数值基组DNP,将基组重叠误差降至最低.在Gaussi-an03的B3LYP/6-31G(d,p)计算中,采用平衡法(Counterpoise)校正基组重叠误差.两种计算方法给出了一致的结果,证实了在使用6-31G(d,p)基组时,一对水分子在平衡距离的基组重叠误差高达8 kJ/mol.为估算色散能的贡献,使用了新近发展的包含色散能的密度泛函的DFT程序deMon计算了五元水分子簇.用多种方法计算出了经基组重叠误差和色散能修正的五元水分子簇的分子间结合能和氢键能的较为精确的势能超曲面,为甲烷和其他气体水合物的分子动力学模拟提供了依据.

Quantum chemical study for water pentamer

The methods B3LYP/6-31G(d,p) of Gaussian03,BLYP/DNP of DMol3,and BLYP/TZVP of deMon are used for the study of binding energy,hydrogen bond,cooperation interaction,dispersion and BSSE in water pentamer.The BSSE and dispersion energy are two key factors in the study of molecular interactions in cluster.In the method BLYP of DMol the large numerical basis set DNP is used to minimize the BSSE.The BSSE in B3LYP/6-31G(d,p) method is corrected by counterpoise(CP) method.The newly developed DFT program deMon,in which the dispersion term is involved in the functional,is used to calculate the dispersion energy in water pentamer.The accurate results of the water-water binding energy hypersurface and potential energy hypersurface of hydrogen bond in water pentamer provide a basis for the empirical potential functions and for the parameters used in the molecular force field of molecular dynamics simulations for gas hydrates.