✦ LIBER ✦

Second-order perturbation on a SDCI calculation

✍ Scribed by Daniel Maynau; Jean-Louis Heully

Publisher: Elsevier Science
Year: 1993
Tongue: English
Weight: 535 KB
Volume: 211
Category: Article
ISSN: 0009-2614
DOI: 10.1016/0009-2614(93)80154-h

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✦ Synopsis

Starting from a SDCI calculation, the SD eigenvector is perturbed by all triply and quadruply excited determinants. EfGciency is promoted through direct CI techniques, however, some flexibility has been kept, making possible the use of various perturbational schemes (here: Epstein-Nesbet and MBller-Plesset) The SDCI starting point avoids divergence problems posed by CCSD(T) and also by purely perturbative methods such as MP4. Several calculations on the potential curves of some molecules (H*O, Nz, F2, Ne,) show that the present method is at least as good as the MP4 or CCSD(T) methods at comparable computational cost.

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