不同算法原子电荷下的1JCH理论计算

摘要

In this study, we calculate atomic net charge of 32 compounds using quantum chemical calculation. A generalized semiempirical relationship was used to compute the nuclear spin-spin coupling constants in these compounds. The obtained semiempirical relationship was then validated using 5 compounds as the test set. The computed results of the 32 training compounds and the 5 test compounds were all in good agreement with the experimental data. It was concluded that semiempirical relationship obtained in this study can be applied to calculate nuclear spin-spin coupling constants and that atomic net charge calculated by charge equilibration method (QEq) provides more reliable results than other parameters.%用一种计算直接键连原子核自旋耦合常数的半经验公式，结合量子化学计算得到的32种有机分子稳定几何构型的7种不同算法下的原子电荷，探究原子电荷算法的不同对1JCH理论计算的影响，拟合出基于7种原子电荷的耦合常数计算公式，并利用拟合公式对5种分子进行了检验。计算结果表明拟合的32种分子及检验的5种分子的耦合常数的计算值均与实验值较好的符合，拟合得到的基于7种原子电荷的计算公式均可以对其他分子体系的耦合常数进行预测。另外，计算结果同样显示原子电荷算法的不同对1JCH理论计算值有一定的影响却不显著，其中基于电荷均衡方法电荷(QEq)得出的耦合常数计算值与实验值的偏差较其它6种原子电荷的小，结果更可靠。