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借助非正交定域分子轨道(简称为LMO)及其伴基所构成的单位算子,得到以LMO为基计算NMR偶合常数的二级微扰理论公式,并计算了CH_4、C_2H_4、C_2H_2分子碳原子和氢原子核上的电荷密度及NMR偶合常数~1J_(CH)。计算结果表明,~1J_(CH)主要由定域于碳原子和氢原子化学键区域的成键与反键LMO所决定,并与LMO在碳原子和氢原子核上的电荷密度乘积成比例。
The second order perturbation theory formula for calculating NMR coupling constants based on LMO is obtained by means of the unit operator composed of non - orthogonal local molecular orbital (LMO) and its companion, and the numerators of CH 4, C 2 H 4 and C 2 H 2 molecules are calculated Charge density and NMR coupling constant on carbon and hydrogen nuclei ~ 1J_ (CH). The calculated results show that ~ 1J_ (CH) is mainly determined by the bond and anti-bond LMO localized in the chemical bond of carbon and hydrogen atoms and proportional to the product of the charge density of LMO on carbon and hydrogen nuclei.