Bond breaking with auxiliary-field quantum Monte Carlo

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dc.creatorAl-Saidi, W. A.
dc.creatorZhang, Shiwei
dc.creatorKrakauer, Henry
dc.date2007-05-19
dc.date.accessioned2026-07-07T08:34:32Z
dc.date.available2026-07-07T08:34:32Z
dc.descriptionBond stretching mimics different levels of electron correlation and provides a challenging testbed for approximate many-body computational methods. Using the recently developed phaseless auxiliary-field quantum Monte Carlo (AF QMC) method, we examine bond stretching in the well-studied molecules BH and N$_2$, and in the H$_{50}$ chain. To control the sign/phase problem, the phaseless AF QMC method constrains the paths in the auxiliary-field path integrals with an approximate phase condition that depends on a trial wave function. With single Slater determinants from unrestricted Hartree-Fock (UHF) as trial wave function, the phaseless AF QMC method generally gives better overall accuracy and a more uniform behavior than the coupled cluster CCSD(T) method in mapping the potential-energy curve. In both BH and N$_2$, we also study the use of multiple-determinant trial wave functions from multi-configuration self-consistent-field (MCSCF) calculations. The increase in computational cost versus the gain in statistical and systematic accuracy are examined. With such trial wave functions, excellent results are obtained across the entire region between equilibrium and the dissociation limit.
dc.description8 pages, 3 figures and 3 tables. Submitted to JCP
dc.identifierhttps://arxiv.org/abs/0705.2827
dc.identifierhttp://arxiv.org/abs/0705.2827
dc.identifierJCP, 127, 144101 (2007).
dc.identifierdoi:10.1063/1.2770707
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/139469
dc.subjectComputational Physics
dc.subjectStrongly Correlated Electrons
dc.subjectChemical Physics
dc.titleBond breaking with auxiliary-field quantum Monte Carlo
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