Variational QMC study of a Hydrogen atom in jellium with comparison to LSDA and LSDA-SIC solutions

TL;DR

This study compares variational quantum Monte Carlo and density functional theory methods in modeling a hydrogen atom in jellium, revealing close immersion energies but differences in density oscillations, and highlights the potential of SIC over LSDA.

Contribution

It provides a direct comparison between VQMC and DFT methods, including LSDA and SIC, for a hydrogen atom in jellium, demonstrating their relative accuracy and differences.

Findings

Immersion energies from VQMC and DFT are within 1 eV, with similar minima.

DFT results tend to overbind compared to VQMC.

SIC shows improved performance over LSDA in energy calculations.

Abstract

A Hydrogen atom immersed in a finite jellium sphere is solved using variational quantum Monte Carlo (VQMC). The same system is also solved using density functional theory (DFT), in both the local spin density (LSDA) and self-interaction correction (SIC) approximations. The immersion energies calculated using these methods, as functions of the background density of the jellium, are found to lie within 1eV of each other with minima in approximately the same positions. The DFT results show overbinding relative to the VQMC result. The immersion energies also suggest an improved performance of the SIC over the LSDA relative to the VQMC results. The atom-induced density is also calculated and shows a difference between the methods, with a more extended Friedel oscillation in the case of the VQMC result.