A quasidegenerate formulation of the second order n-electron valence state perturbation theory approach

被引：330

作者：

Angeli, C ^{[1
]}

Borini, S ^{[1
]}

Cestari, M ^{[1
]}

Cimiraglia, R ^{[1
]}

机构：

[1] Univ Ferrara, Dipartmento Chim, I-44100 Ferrara, Italy

来源：

JOURNAL OF CHEMICAL PHYSICS | 2004年 / 121卷 / 09期

关键词：

D O I：

10.1063/1.1778711

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

The n-electron valence state perturbation theory (NEVPT) is reformulated in a quasidegenerate (QD) approach. The new theory allows the treatment of cases where the proximity of the energies causes artifacts in the zero order description. Problems of quasidegeneration are relevant in the dynamics involving regions at avoided crossings (or conical intersections) and in spectroscopy where the energies and oscillator strengths can be strongly influenced by the mixing of states of different nature. Two test cases are analyzed concerning (a) the ionic-neutral avoided crossing in LiF and (b) the valence/Rydberg mixing in the excited states of ethene. The QD-NEVPT2 is shown to be a useful tool for such systems. (C) 2004 American Institute of Physics.

引用

页码：4043 / 4049

页数：7

共 41 条

[1] 2ND-ORDER PERTURBATION-THEORY WITH A COMPLETE ACTIVE SPACE SELF-CONSISTENT FIELD REFERENCE FUNCTION [J].