Phonons of metallic hydrogen with quantum Monte Carlo

TL;DR

This paper introduces an efficient quantum Monte Carlo-based method for calculating phonons in metallic hydrogen, significantly reducing computational cost while maintaining accuracy.

Contribution

It presents a novel, nearly 100-fold more efficient approach for phonon calculations using QMC, applicable to complex materials like metallic hydrogen.

Findings

The new method reduces computational cost by nearly 100 times.

It accurately computes phonon spectra using only force calculations.

The approach is applicable to systems with challenging energy and length scales.

Abstract

We describe a simple scheme to perform phonon calculations with quantum Monte Carlo (QMC) methods, and demonstrate it on metallic hydrogen. Because of the energy and length scales of metallic hydrogen, and the statistical noise inherent to QMC methods, the conventional manner of calculating force constants is prohibitively expensive. We show that our alternate approach is nearly 100 times more efficient in resolving the force constants needed to calculate the phonon spectrum in the harmonic approximation. This requires only the calculation of atomic forces, as in the conventional approach, and otherwise little or no programmatic modifications.