A study of cumulant approximations to n-electron valence multireference perturbation theory

被引:82
|
作者
Zgid, Dominika [1 ]
Ghosh, Debashree [1 ]
Neuscamman, Eric [1 ]
Chan, Garnet Kin-Lic [1 ]
机构
[1] Cornell Univ, Dept Chem & Chem Biol, Ithaca, NY 14853 USA
来源
JOURNAL OF CHEMICAL PHYSICS | 2009年 / 130卷 / 19期
基金
美国国家科学基金会;
关键词
bond lengths; chromium; electron correlations; nitrogen; organic compounds; perturbation theory; silicon compounds; REDUCED DENSITY-MATRICES; FIELD REFERENCE FUNCTION; FULL CL TREATMENT; CONFIGURATION-INTERACTION; LEVEL SHIFT; SPECTROSCOPIC PROPERTIES; RENORMALIZATION-GROUP; LINEAR POLYENES; WAVE-FUNCTIONS; ENERGY-LEVELS;
D O I
10.1063/1.3132922
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
We investigate the possibility of reducing the complexity of multireference perturbation theory through cumulant based approximations to the high-order density matrices that appear in such theories. Our test cases show that while the cumulant approximated forms are degraded in accuracy relative to the parent theory and exhibit intruder state problems that must be carefully handled, they may provide a route to a simple estimation of dynamic correlation when the parent perturbation theory is infeasible. Nonetheless, further work is clearly needed on better approximations to the denominators in the perturbation theory.
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页数:11
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