Floating spherical Gaussian orbitals based quantum Monte Carlo method in molecular electronic calculations
Journal
The Journal of Chemical Physics
Journal Volume
101
Journal Issue
7
Pages
5910-5918
Date Issued
1994
Author(s)
Leu, S.-Y.
Abstract
We report a new method for fixed-node diffusion quantum Monte Carlo calculation in order to improve the time step-size convergence and the fluctuation problems associated with nodes of wave functions. It adopts floating spherical Gaussian orbitals instead of Slater-type orbitals to guide random walkers (psips). They establish harmonic velocity fields under which psips undergo random walks which are simulated exactly according to the Ornstein–Uhlenbeck process. The nodes of this guiding function are used to guide psips in a novel way; as psips approach to a node, they are swept away therefrom. Explicit enforcement of a sink boundary condition is avoided to some extent, and the behavior of the random walks near nodes is efficiently simulated. The method is illustrated by applying to the ground-state energies of H2, LiH, and HF. The results are excellent compared to previous calculations.
SDGs
Type
journal article