Title | Approaching chemical accuracy with quantum Monte Carlo |
Publication Type | Journal Article |
Year of Publication | 2012 |
Authors | Petruzielo F.R, Toulouse J, Umrigar C.J |
Journal | J. Chem. Phys. |
Volume | 136 |
Date Published | Mar 28 |
ISSN | 0021-9606 |
Abstract | A quantum Monte Carlo study of the atomization energies for the G2 set of molecules is presented. Basis size dependence of diffusion Monte Carlo atomization energies is studied with a single determinant Slater-Jastrow trial wavefunction formed from Hartree-Fock orbitals. With the largest basis set, the mean absolute deviation from experimental atomization energies for the G2 set is 3.0 kcal/mol. Optimizing the orbitals within variational Monte Carlo improves the agreement between diffusion Monte Carlo and experiment, reducing the mean absolute deviation to 2.1 kcal/mol. Moving beyond a single determinant Slater-Jastrow trial wavefunction, diffusion Monte Carlo with a small complete active space Slater-Jastrow trial wavefunction results in near chemical accuracy. In this case, the mean absolute deviation from experimental atomization energies is 1.2 kcal/mol. It is shown from calculations on systems containing phosphorus that the accuracy can be further improved by employing a larger active space. (C) 2012 American Institute of Physics. {[}http://dx.doi.org/10.1063/1.3697846] |
DOI | 10.1063/1.3697846 |
Investigating Quantum Monte Carlo, Electronic Structure Theory