Development of an efficient linear response approach to the Hilbert space multi-reference coupled-cluster theory

Shamasundar, K. R. ; Pal, Sourav (2001) Development of an efficient linear response approach to the Hilbert space multi-reference coupled-cluster theory Journal of Chemical Physics, 114 (5). pp. 1981-1988. ISSN 0021-9606

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Official URL: http://link.aip.org/link/JCPSA6/v114/i5/p1981/s1

Related URL: http://dx.doi.org/10.1063/1.1336565

Abstract

In this paper, we use an analytic linear response to develop efficient expressions for calculating a first-order energy response using the multi-reference Hilbert space coupled-cluster (HSMRCC) theory. Equations for the first-order response are derived and their diagrammatic evaluation is outlined. The Z-vector formalism used in SRCC to eliminate the explicit presence of a cluster amplitude response in favor of a de-excitation operator is generalized to HSMRCC and applied here. We also discuss several aspects of the Z-vector and outline different ways of introducing the technique and appropriateness of these in various circumstances. Efficient expressions for the energy response in terms of state-dependent effective CC density matrices are presented. We also compare our approach with Szalay's approach based on the generalized Hellmann-Feynmann theorem and discuss the advantages of our approach.

Item Type:Article
Source:Copyright of this article belongs to American Institute of Physics.
ID Code:25894
Deposited On:04 Dec 2010 11:04
Last Modified:05 Mar 2011 05:36

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