dorsal/arxiv
View SchemaAuxiliary-field quantum Monte Carlo calculations of molecular systems with a Gaussian basis
| Authors | W. A. Al-Saidi, Shiwei Zhang, Henry Krakauer |
|---|---|
| Categories | |
| ArXiv ID | physics/0603055 |
| URL | https://arxiv.org/abs/physics/0603055 |
| DOI | 10.1063/1.2200885 |
| Journal | J. Chem. Phys. 124, 224101 (2006) |
Abstract
We 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).
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"abstract": "We extend the recently introduced phaseless auxiliary-field quantum Monte\nCarlo (QMC) approach to any single-particle basis, and apply it to molecular\nsystems with Gaussian basis sets. QMC methods in general scale favorably with\nsystem size, as a low power. A QMC approach with auxiliary fields in principle\nallows an exact solution of the Schrodinger equation in the chosen basis.\nHowever, the well-known sign/phase problem causes the statistical noise to\nincrease exponentially. The phaseless method controls this problem by\nconstraining the paths in the auxiliary-field path integrals with an\napproximate phase condition that depends on a trial wave function. In the\npresent calculations, the trial wave function is a single Slater determinant\nfrom a Hartree-Fock calculation. The calculated all-electron total energies\nshow typical systematic errors of no more than a few milli-Hartrees compared to\nexact results. At equilibrium geometries in the molecules we studied, this\naccuracy is roughly comparable to that of coupled-cluster with single and\ndouble excitations and with non-iterative triples, CCSD(T). For stretched bonds\nin H$_2$O, our method exhibits better overall accuracy and a more uniform\nbehavior than CCSD(T).",
"arxiv_id": "physics/0603055",
"authors": [
"W. A. Al-Saidi",
"Shiwei Zhang",
"Henry Krakauer"
],
"categories": [
"physics.comp-ph",
"cond-mat.str-el",
"physics.chem-ph"
],
"doi": "10.1063/1.2200885",
"journal_ref": "J. Chem. Phys. 124, 224101 (2006)",
"title": "Auxiliary-field quantum Monte Carlo calculations of molecular systems with a Gaussian basis",
"url": "https://arxiv.org/abs/physics/0603055"
},
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