Equation of motion theory for excited states in variational Monte Carlo and the Jastrow antisymmetric geminal power in Hilbert space

TL;DR

This paper develops an equation of motion approach for excited states within variational Monte Carlo, applying it to the Jastrow antisymmetric geminal power, and compares its accuracy to established methods across small molecules.

Contribution

It introduces a novel equation of motion formalism for excited states in variational Monte Carlo and demonstrates its application to the Jastrow antisymmetric geminal power.

Findings

Single excitation energies are between configuration interaction singles and EOM-CCSD in accuracy.

Double excitation energies have errors comparable to coupled cluster methods.

The method shows promise for accurate excited state calculations in quantum chemistry.

Abstract

An equation of motion formalism for excited states in variational Monte Carlo is derived and a pilot implementation for the Jastrow-modified antisymmetric geminal power is tested. In single excitations across a range of small molecules, this combination is shown to be intermediate in accuracy between configuration interaction singles and equation of motion coupled cluster with singles and doubles. For double excitations, energy errors are found to be similar to those for coupled cluster.