Electronic excitation spectra of molecular hydrogen in phase I from quantum Monte Carlo and many-body perturbation methods

In this talk, I will present the electronic excitations in solid molecular hydrogen at room temperature and pressures ranging from 5 to 90 GPa, calculated using quantum Monte Carlo methods and many-body perturbation theory. Our results reveal a crossover from a wide-gap insulator to a semiconductor, illustrating a shift in the nature of excitations from localized molecular to delocalized states. Based on the computed energy gaps and optical properties, I will discuss and interpret recent inelastic X-ray scattering (IXS) experimental results [1]. This work demonstrates the capability of accurately predicting band gaps in many-body systems with strong zero-point and thermal effects [2].

[1] B. Li, et al, PRL 126, 036402 (2021)

[2] V. Gorelov et al, PRB 109, L241111 (2024)