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A comparison of the efficiency and accuracy of the quadratic configuration interaction (QCISD), coupled cluster (CCSD), and Brueckner coupled cluster (BCCD) methods

✍ Scribed by Claudia Hampel; Kirk A. Peterson; Hans-Joachim Werner

Publisher: Elsevier Science
Year: 1992
Tongue: English
Weight: 1022 KB
Volume: 190
Category: Article
ISSN: 0009-2614
DOI: 10.1016/0009-2614(92)86093-w

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✦ Synopsis

The coupled-cluster method restricted to single and double excitations from a closed-shell reference function (CCSD) and the corresponding quadratic configuration interaction method (QCISD) are formulated in terms of quantities which can be computed directly from the two-electron integrals in A0 basis. A simple yet effective method to accelerate convergence in Brueckner coupled-cluster (BCCD) calculations is also described. Using this procedure BCCD calculations require no more effort than CCSD calculations. In order to compare the accuracy of all three methods potential energy functions and spectroscopic constants have been calculated for NS, CO, F2, and HF using large basis sets.

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