Dunlap Brett I, Karna Shashi P, Zope Rajendra R
Code 6189, Theoretical Chemistry Section, U.S. Naval Research Laboratory, Washington, DC 20375-5342, USA.
J Chem Phys. 2006 Dec 7;125(21):214104. doi: 10.1063/1.2403854.
Molecular dipole moments of analytic density-functional theory are investigated. The effect of element-dependent exchange potentials on these moments are examined by comparison with conventional quantum-chemical methods and experiment for the subset of the extended G2 set of molecules that have nonzero dipole moment. Fitting the Kohn-Sham [Phys. Rev. 140, A1133 (1965)] potential itself makes a mean absolute error of less than 0.1 D. Variation of alpha (Slater's [Phys. Rev. 81, 385 (1951)] exchange parameter) values has far less effect on dipole moments than on energies. It is argued that in variable alpha methods one should choose the smaller of the two rather than the geometric mean of the two alpha values for the heteroatomic part of the linear-combination-atomic-orbital density. Calculations on the dipole moment of NH(2)(CH)(24)NO(2) are consistent with earlier calculations and show that varying the differences between alpha values for atoms with different atomic numbers has only short-ranged electrostatic effects.
研究了解析密度泛函理论的分子偶极矩。通过与传统量子化学方法以及对扩展G2分子集中具有非零偶极矩的子集进行实验比较，研究了元素相关交换势对这些偶极矩的影响。拟合Kohn-Sham [《物理评论》140, A1133 (1965)] 势本身会产生小于0.1 D的平均绝对误差。α（斯莱特 [《物理评论》81, 385 (1951)] 交换参数）值的变化对偶极矩的影响远小于对能量的影响。有人认为，在可变α方法中，对于线性组合原子轨道密度的杂原子部分，应该选择两者中较小的α值，而不是两个α值的几何平均值。对NH(2)(CH)(24)NO(2)偶极矩的计算与早期计算结果一致，表明改变不同原子序数原子的α值之间的差异仅具有短程静电效应。
