Excitation energies of H2O, N-2 and C-2 in full configuration interaction and coupled cluster theory

被引：221

作者：

Christiansen, O ^{[1
]}

Koch, H ^{[1
]}

Jorgensen, P ^{[1
]}

Olsen, J ^{[1
]}

机构：

[1] LUND UNIV,CTR CHEM,S-22100 LUND,SWEDEN

来源：

CHEMICAL PHYSICS LETTERS | 1996年 / 256卷 / 1-2期

关键词：

D O I：

10.1016/0009-2614(96)00394-6

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：

Singlet excitation energies of H2O, N-2 and C-2 have been calculated in full configuration interaction (FCI) and in the coupled cluster model hierarchy CCS, CC2, CCSD and CC3. Excitation energies are improved at each level in the coupled cluster hierarchy, with a decrease in the error compared to FCI of about a factor of three at each level. This decrease is in accordance with the fact that the excitations in CCS, CC2, CCSD and CC3 are correct through higher and higher order in the fluctuation potential, and that more and more complete cluster treatments are used. Non-iterative triples corrections to the CCSD excitation energies are compared with the iterative triples model CC3 and FCI. The CCSDR(3) approach recovers the major part of the correlation improvement obtained in the CC3 model.

引用

页码：185 / 194

页数：10