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

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 enables us to build multi-reference wave functions and analyze the impact of both electron correlations and the spin-orbit terms.