Perturbatively selected CI as an optimal source for externally corrected CCSD

Autor:	Josep Planelles, J.-P. Malrieu, Guillermo Peris, Josef Paldus
Rok vydání:	1999
Předmět:	Coupled cluster Basis (linear algebra) Chemistry General Physics and Astronomy Single bond Physical and Theoretical Chemistry Atomic physics Configuration interaction Ground state Triple bond Wave function Potential energy
Zdroj:	The Journal of Chemical Physics. 110:11708-11716
ISSN:	1089-7690 0021-9606
DOI:	10.1063/1.479116
Popis:	Perturbatively selected configuration interaction (PSCI) is used as a source of higher than pair clusters in the externally corrected coupled cluster method with singles and doubles (ecCCSD). This significantly decreases the dimension of the standard multireference (MR) CISD that is employed by the so-called reduced MR (RMR) CCSD method, thus enabling the use of relatively large active spaces. The performance of the proposed PSCI CCSD method is illustrated by considering the ground state potential energy curves of the HF molecule using DZP and cc-pVTZ basis sets (breaking of a single bond), and of the N2 molecule using a TZ basis set (breaking of a triple bond). It is shown that notwithstanding a large reduction in the dimension of the external source, the accuracy of the resulting ecCCSD energies is almost the same as that obtained when correcting with the full MR CISD wave function.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::c27fe9c196ae4783a6e46aba6c9ba878 https://doi.org/10.1063/1.479116 Zobrazit plný text záznamu