Auxiliary-field based trial wave functions in quantum Monte Carlo calculations

TL;DR

This paper introduces a new method for generating Jastrow-type trial wave functions in auxiliary-field quantum Monte Carlo, improving energy accuracy by efficiently sampling significant determinants.

Contribution

The authors develop a scheme to incorporate Jastrow correlations into auxiliary-field QMC using auxiliary fields, enabling compact multi-determinant trial wave functions.

Findings

Sampling significant determinants reduces energy errors.

Method is adaptable to various two-body Jastrow factors.

Applicable to diverse model and chemical systems.

Abstract

Quantum Monte Carlo (QMC) algorithms have long relied on Jastrow factors to incorporate dynamic correlation into trial wave functions. While Jastrow-type wave functions have been widely employed in real-space algorithms, they have seen limited use in second-quantized QMC methods, particularly in projection methods that involve a stochastic evolution of the wave function in imaginary time. Here we propose a scheme for generating Jastrow-type correlated trial wave functions for auxiliary-field QMC methods. The method is based on decoupling the two-body Jastrow into one-body projectors coupled to auxiliary fields, which then operate on a single determinant to produce a multi-determinant trial wave function. We demonstrate that intelligent sampling of the most significant determinants in this expansion can produce compact trial wave functions that reduce errors in the calculated energies. Our technique may be readily generalized to accommodate a wide range of two-body Jastrow factors and applied to a variety of model and chemical systems.