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Analytical energy gradients for a unitary coupled-cluster theory

✍ Scribed by Mark R. Hoffmann; Jack Simons

Publisher: Elsevier Science
Year: 1987
Tongue: English
Weight: 350 KB
Volume: 142
Category: Article
ISSN: 0009-2614
DOI: 10.1016/0009-2614(87)80642-5

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✦ Synopsis

Our recently developed and tested unitary multiconfigurational coupled-cluster electronic wavefunction method is extended to permit, for the first time, the analytical evaluation of energy derivatives. The unitary nature of this method admits a variational energy functional whose stationary nature plays a key role in simplifying our derivation. Explicit expressions are given for the gradient (first energy derivative) for both the full unitary coupled cluster and its coupled electron pair approximation (CEPA) .

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