Multireference state-specific Mukherjee's coupled cluster method with noniterative triexcitations using uncoupled approximation

0361408 - ÚFCH JH 2012 RIV US eng J - Journal Article
Bhaskaran-Nair, Kiran - Demel, Ondřej - Šmydke, Jan - Pittner, Jiří
Multireference state-specific Mukherjee's coupled cluster method with noniterative triexcitations using uncoupled approximation.
Journal of Chemical Physics. Roč. 134, č. 15 (2011), s. 154106. ISSN 0021-9606. E-ISSN 1089-7690
R&D Projects: GA ČR GA203/07/0070; GA ČR GPP208/10/P041
Institutional research plan: CEZ:AV0Z40400503
Keywords : Schroedinger perturbation theory * size-extensitivity correction * singlet-triplet separation
Subject RIV: CF - Physical ; Theoretical Chemistry
Impact factor: 3.333, year: 2011

A new version of the multireference Mukherjee's coupled cluster method with perturbative triexcitations has been formulated, which is based on the uncoupled approximation applied to the triples equation. In contrast to the method developed by Evangelista et al. [J. Chem. Phys. 132, 074107 (2010)], the proposed approach does not require to solve the equation for T(3) amplitudes iteratively, yet yields results of essentially the same quality. The method, abbreviated as MR MkCCSD(Tu), has been implemented in the ACES II program package and its assessment has been performed on the BeH(2) model and on the tetramethyleneethane molecule.
Permanent Link: http://hdl.handle.net/11104/0198725