价键结构函数与键函数 Ⅰ.理论处理及甲烷的应用实例

Valence Bond Structure Function and Bonded Function Ⅰ. Theoretical Method and Application to Methane

采用键函数形式对键表进行逐级展开,其中键函数的强正交积作为零级波函数,进而构造了各级校正函数以描述多对键之间的相关作用.同时采用Heitler-London函数作为键函数,对甲烷进行了键表计算,结果表明CH_4中一、二、三级校正能近似有4:2:-1的关系,即校正函数的收敛性能较好.

The bonded tableau is expanded in a series of bonded functions of different order, where the zero-order wavefunction of a system is expressed as an asymmetric product of strong-orthogonal geminals (APSG), moreover, many-order correction wavefunctions are constructed to describe the correlation interactions among several bonds. As an application, a Heitler?London-like function was chosen as the bonded function to perform the calculation of methane molecule. The results show that the first to the third correction energies consist in an approaximate ratio of 4 : 2 : -1. Thus the convergence of the correction wavefunctions is moderately good.