摘要
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.
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.
出处
《波谱学杂志》
CAS
CSCD
北大核心
2014年第3期397-406,共10页
Chinese Journal of Magnetic Resonance
基金
安徽高校省级自然科学基金重点资助项目(KJ2010A2229)
关键词
原子电荷
核自旋耦合常数
量子化学计算
s成分
atomic net charge
nuclear spin-spin coupling constant
quantum chemical calculation
s-character