Wesolowski Tomasz A
Département de Chimie Physique, Université de Genève, 30, quai Ernest-Ansermet, CH-1211 Genève 4, Switzerland.
J Chem Phys. 2014 May 14;140(18):18A530. doi: 10.1063/1.4870014.
Frozen-Density-Embedding Theory (FDET) is a formalism to obtain the upper bound of the ground-state energy of the total system and the corresponding embedded wavefunction by means of Euler-Lagrange equations [T. A. Wesolowski, Phys. Rev. A 77(1), 012504 (2008)]. FDET provides the expression for the embedding potential as a functional of the electron density of the embedded species, electron density of the environment, and the field generated by other charges in the environment. Under certain conditions, FDET leads to the exact ground-state energy and density of the whole system. Following Perdew-Levy theorem on stationary states of the ground-state energy functional, the other-than-ground-state stationary states of the FDET energy functional correspond to excited states. In the present work, we analyze such use of other-than-ground-state embedded wavefunctions obtained in practical calculations, i.e., when the FDET embedding potential is approximated. Three computational approaches based on FDET, that assure self-consistent excitation energy and embedded wavefunction dealing with the issue of orthogonality of embedded wavefunctions for different states in a different manner, are proposed and discussed.
冷冻密度嵌入理论（FDET）是一种通过欧拉 - 拉格朗日方程获得总系统基态能量上限及相应嵌入波函数的形式体系 [T. A. Wesolowski，《物理评论A》77(1)，012504 (2008)]。FDET给出了嵌入势的表达式，它是嵌入物种的电子密度、环境的电子密度以及环境中其他电荷产生的场的泛函。在某些条件下，FDET能得到整个系统精确的基态能量和密度。根据关于基态能量泛函稳态的佩德韦 - 利维定理，FDET能量泛函的非基态稳态对应于激发态。在本工作中，我们分析了在实际计算中获得的非基态嵌入波函数的这种用途，即当FDET嵌入势被近似时的情况。提出并讨论了基于FDET的三种计算方法，它们以不同方式处理不同态嵌入波函数的正交性问题，确保了自洽激发能和嵌入波函数。
