Pernal Katarzyna, Baerends Evert Jan
Afdeling Theoretische Chemie, Vrije Universiteit, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
J Chem Phys. 2006 Jan 7;124(1):14102. doi: 10.1063/1.2137325.
Starting from the variational equations for the natural occupation numbers and the recently proposed eigenequations for the natural spin-orbitals, we derive coupled-perturbed density-matrix equations that furnish a linear response of the one-electron reduced density matrix to a static perturbation when the total energy is a functional of the one-electron reduced density matrix. Cases when some occupation numbers achieve exactly 0 or 1 or when the total number of the particles in a system is not preserved are taken into consideration. The scheme is applied to computing static polarizabilities from two simple density-matrix functionals. The behavior of the functionals is erratic and they provide only little or no improvement over the coupled-perturbed Hartree-Fock results.
从自然占据数的变分方程以及最近提出的自然自旋轨道的本征方程出发，我们推导了耦合微扰密度矩阵方程，当总能量是单电子约化密度矩阵的泛函时，该方程给出了单电子约化密度矩阵对静态微扰的线性响应。我们考虑了某些占据数恰好为0或1的情况，以及系统中粒子总数不守恒的情况。该方案被应用于从两个简单的密度矩阵泛函计算静态极化率。这些泛函的表现不稳定，与耦合微扰哈特里 - 福克结果相比，它们仅提供了很少的改进或没有改进。
