Analytic energy derivatives in many‐body methods. I. First derivatives

Autor:	Rodney J. Bartlett, Gary W. Trucks, Edward A. Salter
Rok vydání:	1989
Předmět:	Many-body problem Amplitude Classical mechanics General Physics and Astronomy Electronic structure Physical and Theoretical Chemistry Perturbation theory Configuration interaction Quantum chemistry Energy (signal processing) Second derivative Mathematical physics Mathematics
Zdroj:	The Journal of Chemical Physics. 90:1752-1766
ISSN:	1089-7690 0021-9606
DOI:	10.1063/1.456069
Popis:	Second derivatives of the energy correspond to second‐order response properties and molecular force constants. Currently, both the theory and application of analytic second derivatives in many‐body methods are limited to second‐order perturbation theory. The general theory of analytic second derivatives for the coupled‐cluster (CC) model is presented. The analytic expressions for the second derivative of the energy are given in terms of the response (or ‘‘relaxed’’) density, discussed in part I, and the first‐derivative t amplitudes for efficient evaluation. Explicit expressions for the second derivatives of the coupled‐cluster singles, doubles, and linearized triples model (CCSDT‐1) are presented. Analytic derivatives for the finite‐order MBPT(3) and MBPT(4) models are derived as special cases of the theory.
Databáze:	OpenAIRE
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