Projector quantum Monte Carlo with averaged vs. explicit spin-orbit effects: applications to tungsten molecular systems

TL;DR

This paper introduces a projector quantum Monte Carlo method incorporating spin-orbit interactions, enabling detailed electronic structure calculations of heavy-element molecules with significant relativistic effects.

Contribution

The paper develops a novel quantum Monte Carlo approach that explicitly includes spin-orbit effects using a fixed-phase approximation with two-component spinors.

Findings

Successfully applied to WO and W₂ molecules

Analyzed the impact of electron correlations and spin-orbit effects

Enabled multi-reference wave function construction for heavy elements

Abstract

We present a recently developed projector quantum Monte Carlo method for calculations of electronic structure in systems with spin-orbit interactions. The method solves for many-body eigenstates in the presence of spin-orbit using the fixed-phase approximation.The trial wave function is built from two-component spinors and explicit Jastrow correlation factors while the core electrons are eliminated by relativistic effective core potentials with explicit spin-orbit terms. We apply this method to WO and W$_2$ molecules that enable us to build multi-reference wave functions and analyze in detail the impact of both electron correlations and of spin-orbit terms. These developments open new opportunities for calculations of systems with significant spin-orbit effects by many-body quantum Monte Carlo methods.