Electronic excitation spectra of molecular hydrogen in Phase I from Quantum Monte Carlo and Many-Body perturbation methods

TL;DR

This paper investigates the electronic excitation spectra of solid molecular hydrogen in Phase I under various pressures using advanced computational methods, successfully predicting band gaps and spectral features consistent with experimental data.

Contribution

It demonstrates the effectiveness of Quantum Monte Carlo and Many-Body Perturbation Theory in accurately modeling electronic excitations in molecular solids under pressure.

Findings

Computed band gaps agree with experimental measurements.

Transition from insulator to semiconductor observed with increasing pressure.

Spectral features match experimental spectra across pressure range.

Abstract

We study the electronic excitation spectra in solid molecular hydrogen (phase I) at ambient temperature and 5-90 GPa pressures using Quantum Monte Carlo methods and Many-Body Perturbation Theory. In this range, the system changes from a wide gap molecular insulator to a semiconductor, altering the nature of the excitations from localized to delocalized. Computed gaps and spectra agree with experiments, proving the ability to predict accurately band gaps of many-body systems in presence of nuclear quantum and thermal effects.