Auxiliary-field quantum Monte Carlo calculations of molecular systems with a Gaussian basis

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dc.creatorAl-Saidi, W. A.
dc.creatorZhang, Shiwei
dc.creatorKrakauer, Henry
dc.date2006-03-07
dc.date2006-05-10
dc.date.accessioned2026-07-07T07:07:37Z
dc.date.available2026-07-07T07:07:37Z
dc.descriptionWe extend the recently introduced phaseless auxiliary-field quantum Monte Carlo (QMC) approach to any single-particle basis, and apply it to molecular systems with Gaussian basis sets. QMC methods in general scale favorably with system size, as a low power. A QMC approach with auxiliary fields in principle allows an exact solution of the Schrodinger equation in the chosen basis. However, the well-known sign/phase problem causes the statistical noise to increase exponentially. The phaseless method controls this problem by constraining the paths in the auxiliary-field path integrals with an approximate phase condition that depends on a trial wave function. In the present calculations, the trial wave function is a single Slater determinant from a Hartree-Fock calculation. The calculated all-electron total energies show typical systematic errors of no more than a few milli-Hartrees compared to exact results. At equilibrium geometries in the molecules we studied, this accuracy is roughly comparable to that of coupled-cluster with single and double excitations and with non-iterative triples, CCSD(T). For stretched bonds in H$_2$O, our method exhibits better overall accuracy and a more uniform behavior than CCSD(T).
dc.description11 pages, 5 figures. submitted to JCP
dc.identifierhttps://arxiv.org/abs/physics/0603055
dc.identifierhttp://arxiv.org/abs/physics/0603055
dc.identifierJ. Chem. Phys. 124, 224101 (2006)
dc.identifierdoi:10.1063/1.2200885
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/110458
dc.subjectComputational Physics
dc.subjectStrongly Correlated Electrons
dc.subjectChemical Physics
dc.titleAuxiliary-field quantum Monte Carlo calculations of molecular systems with a Gaussian basis
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