Adding electron-nuclear cusps to Gaussian basis functions for molecular quantum Monte Carlo calculations

Abstract

A scheme for imposing the electron-nuclear cusp condition in molecular quantum Monte Carlo (QMC) calculations using Gaussian basis functions is presented. While the constraints proposed by Ma et al. [J. Chem. Phys. 122, 224322 (2005)] have been used, in our scheme the basis functions are modified instead of the molecular orbitals. This method can also be directly applied to density matrix-based QMC calculations whose effort scales linearly for calculating the local energy [J. Kussmann et al., Phys. Rev. B 75, 165107 (2007)]. Furthermore, virtually no additional computational effort in the evaluation of the local energy arises within QMC calculations.