Shifted-contour auxiliary field Monte Carlo for {ital ab initio} electronic structure: Straddling the sign problem
Journal Article
·
· Journal of Chemical Physics
- Department of Chemistry, University of California and the Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569 (United States)
The auxiliary field Monte Carlo (AFMC) technique has advantages over other {ital ab initio} quantum Monte Carlo methods for fermions, as it does not seem to require approximations for alleviating the sign problem and is directly applicable to excited states. Yet, the method is severely limited by a numerical instability, a numerical sign problem, prohibiting application to realistic electronic structure systems. Recently, the {ital shifted contour auxiliary field method} (SC-AFMC) was proposed for overcoming this instability. Here we develop a theory for the AFMC stabilization, explaining the success of SC-AFMC. We show that the auxiliary fields can be shifted into the complex plane in a manner that considerably stabilizes the Monte Carlo integration using the exact one-electron density. Practical stabilization can be achieved when an approximate Hartree{endash}Fock density is used, proposing that an overwhelming part of the sign problem is removed by taking proper account of the Fermion mean-field contribution. The theory is demonstrated by application to H{sub 2}.{copyright} {ital 1998 American Institute of Physics.}
- OSTI ID:
- 659305
- Journal Information:
- Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 15 Vol. 109; ISSN JCPSA6; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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