Compact and Flexible Basis Functions for Quantum Monte Carlo Calculations

Abstract

Molecular calculations in quantum Monte Carlo frequently employ a mixed basis consisting of contracted and primitive Gaussian functions. While standard basis sets of varying size and accuracy are available in the literature, we demonstrate that reoptimizing the primitive function exponents within quantum Monte Carlo yields more compact basis sets for a given accuracy. Particularly large gains are achieved for highly excited states. For calculations requiring non-diverging pseudopotentials, we introduce Gauss-Slater basis functions that behave as Gaussians at short distances and Slaters at long distances. These basis functions further improve the energy and fluctuations of the local energy for a given basis size. Gains achieved by exponent optimization and Gauss-Slater basis use are exemplified by calculations for the ground state of carbon, the lowest lying excited states of carbon with ${}^5{S}^o$, ${}^3{P}^o$, ${}^1{D}^o$, ${}^3{F}^o$ symmetries, carbon dimer, and naphthalene. Basis size reduction enables quantum Monte Carlo treatment of larger molecules at high accuracy.

8 Pages, 2 Figures, 9 Tables

References in corpus (2)

• Optimization of quantum Monte Carlo wave functions by energy minimization
• Full optimization of Jastrow-Slater wave functions with application to the first-row atoms and homonuclear diatomic molecules

Cited by in corpus (5)

• Strong electronic correlation in the Hydrogen chain: a variational Monte Carlo study
• Approaching Chemical Accuracy with Quantum Monte Carlo
• Fate of the open-shell singlet ground state in the experimentally accessible acenes: a quantum Monte Carlo study
• Geminal embedding scheme for optimal atomic basis set construction in correlated calculations
• Basis set construction for molecular electronic structure theory: Natural orbital and Gauss-Slater basis for smooth pseudpotentials