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Title: Using full configuration interaction quantum Monte Carlo in a seniority zero space to investigate the correlation energy equivalence of pair coupled cluster doubles and doubly occupied configuration interaction

Over the past few years, pair coupled cluster doubles (pCCD) has shown promise for the description of strong correlation. This promise is related to its apparent ability to match results from doubly occupied configuration interaction (DOCI), even though the latter method has exponential computational cost. In this paper, by modifying the full configuration interaction quantum Monte Carlo algorithm to sample only the seniority zero sector of Hilbert space, we show that the DOCI and pCCD energies are in agreement for a variety of 2D Hubbard models, including for systems well out of reach for conventional configuration interaction algorithms. Our calculations are aided by the sign problem being much reduced in the seniority zero space compared with the full space. Finally, we present evidence for this and then discuss the sign problem in terms of the wave function of the system which appears to have a simplified sign structure.
Authors:
 [1] ;  [1] ;  [1]
  1. Rice Univ., Houston, TX (United States). Dept. of Chemistry. Dept. of Physics and Astronomy
Publication Date:
Grant/Contract Number:
FG02-04ER15523
Type:
Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 144; Journal Issue: 9; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Research Org:
Rice Univ., Houston, TX (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; stochastic processes; density-matrix; band gap; Hilbert space; coupled-cluster methods; configuration interaction; correlation energy; Monte Carlo methods; many electron systems; zero point energy
OSTI Identifier:
1470135
Alternate Identifier(s):
OSTI ID: 1240474

Shepherd, James J., Henderson, Thomas M., and Scuseria, Gustavo E.. Using full configuration interaction quantum Monte Carlo in a seniority zero space to investigate the correlation energy equivalence of pair coupled cluster doubles and doubly occupied configuration interaction. United States: N. p., Web. doi:10.1063/1.4942770.
Shepherd, James J., Henderson, Thomas M., & Scuseria, Gustavo E.. Using full configuration interaction quantum Monte Carlo in a seniority zero space to investigate the correlation energy equivalence of pair coupled cluster doubles and doubly occupied configuration interaction. United States. doi:10.1063/1.4942770.
Shepherd, James J., Henderson, Thomas M., and Scuseria, Gustavo E.. 2016. "Using full configuration interaction quantum Monte Carlo in a seniority zero space to investigate the correlation energy equivalence of pair coupled cluster doubles and doubly occupied configuration interaction". United States. doi:10.1063/1.4942770. https://www.osti.gov/servlets/purl/1470135.
@article{osti_1470135,
title = {Using full configuration interaction quantum Monte Carlo in a seniority zero space to investigate the correlation energy equivalence of pair coupled cluster doubles and doubly occupied configuration interaction},
author = {Shepherd, James J. and Henderson, Thomas M. and Scuseria, Gustavo E.},
abstractNote = {Over the past few years, pair coupled cluster doubles (pCCD) has shown promise for the description of strong correlation. This promise is related to its apparent ability to match results from doubly occupied configuration interaction (DOCI), even though the latter method has exponential computational cost. In this paper, by modifying the full configuration interaction quantum Monte Carlo algorithm to sample only the seniority zero sector of Hilbert space, we show that the DOCI and pCCD energies are in agreement for a variety of 2D Hubbard models, including for systems well out of reach for conventional configuration interaction algorithms. Our calculations are aided by the sign problem being much reduced in the seniority zero space compared with the full space. Finally, we present evidence for this and then discuss the sign problem in terms of the wave function of the system which appears to have a simplified sign structure.},
doi = {10.1063/1.4942770},
journal = {Journal of Chemical Physics},
number = 9,
volume = 144,
place = {United States},
year = {2016},
month = {3}
}