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Canonical transformation theory for multireference problems

Yanai, Takeshi and Chan, Garnet Kin-Lic (2006) Canonical transformation theory for multireference problems. Journal of Chemical Physics, 124 (19). Art. No. 194106. ISSN 0021-9606. doi:10.1063/1.2196410.

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We propose a theory to describe dynamic correlations in bonding situations where there is also significant nondynamic character. We call this the canonical transformation (CT) theory. When combined with a suitable description of nondynamic correlation, such as given by a complete-active-space self-consistent Field (CASSCF) or density matrix renormalization group wave function, it provides a theory to describe bonding situations across the entire potential energy surface with quantitative accuracy for both dynamic and nondynamic correlation. The canonical transformation theory uses a unitary exponential ansatz, is size consistent, and has a computational cost of the same order as a single-reference coupled cluster theory with the same level of excitations. Calculations using the CASSCF based CT method with single and double operators for the potential energy curves for water and nitrogen molecules, the BeH_2 insertion reaction, and hydrogen fluoride and boron hydride bond breaking, consistently yield quantitative accuracies typical of equilibrium region coupled cluster theory, but across all geometries, and better than obtained with multireference perturbation theory.

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Chan, Garnet Kin-Lic0000-0001-8009-6038
Additional Information:© 2006 American Institute of Physics. Received 27 January 2006; accepted 22 March 2006; published online 16 May 2006. We would like to thank S. R. White for useful discussions and Cornell University for financial support.
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Cornell UniversityUNSPECIFIED
Issue or Number:19
Record Number:CaltechAUTHORS:20161221-080745056
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:73048
Deposited By: Donna Wrublewski
Deposited On:21 Dec 2016 18:14
Last Modified:11 Nov 2021 05:10

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