Towards a Systematic Improvement of the Fixed-Node Approximation in Diffusion Monte Carlo for Solids -- A Case Study In Diamond
Abstract
While Diffusion Monte Carlo (DMC) is in principle an exact stochastic method for \textit{ab initio} electronic structure calculations, in practice the fermionic sign problem necessitates the use of the fixed-node approximation and trial wavefunctions with approximate nodes (or zeros) must be used. This approximation introduces a variational error in the energy that potentially can be tested and systematically improved. Here, we present a computational method that produces trial wavefunctions with systematically improvable nodes for DMC calculations of periodic solids. These trial wavefunctions are efficiently generated with the configuration interaction using a perturbative selection made iteratively (CIPSI) method. A simple protocol in which both exact and approximate results for finite supercells are used to extrapolate to the thermodynamic limit is introduced.
Cite
@article{arxiv.2007.11673,
title = {Towards a Systematic Improvement of the Fixed-Node Approximation in Diffusion Monte Carlo for Solids -- A Case Study In Diamond},
author = {Anouar Benali and Kevin Gasperich and Kenneth D. Jordan and Thomas Applencourt and Ye Luo and M. Chandler Bennett and Jaron T. Krogel and Luke Shulenburger and Paul R. C. Kent and Pierre-François Loos and Anthony Scemama and Michel Caffarel},
journal= {arXiv preprint arXiv:2007.11673},
year = {2020}
}