Coupled-cluster theory employing approximate Integrals: An approach to avoid the input/output and storage bottlenecks

Alistair P. Rendell, Timothy J. Lee

Research output: Contribution to journalArticle

152 Citations (Scopus)

Abstract

By representing orbital products in an expansion basis, certain classes of two-electron integrals are approximated for use in CCSD(T) calculations (singles and doubles coupled-cluster plus a perturbational estimate of the effects of connected triple excitations). This leads to a very large reduction in disk storage and input/output requirements, with usually only a modest increase in computational effort. The new procedure will allow-very large CCSD(T) calculations to be undertaken, limited only by available processor time. Using the molecular basis as the expansion basis, explicit numerical comparisons of equilibrium geometries, harmonic frequencies, and energy differences indicate that the error due to the use of approximate integrals is less than the error associated with truncation of the molecular basis set.

Original languageEnglish
Pages (from-to)400-408
Number of pages9
JournalThe Journal of Chemical Physics
Volume101
Issue number1
DOIs
Publication statusPublished - 1 Jul 1994
Externally publishedYes

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