Quantum Monte Carlo calculation of Compton profiles of solid lithium

TL;DR

This study uses quantum Monte Carlo methods to analyze electron correlations in lithium's Compton profiles, finding that correlation effects alone do not explain experimental discrepancies, suggesting other factors are involved.

Contribution

It provides a pseudopotential quantum Monte Carlo analysis of lithium's electron momentum distribution, challenging previous GW results and highlighting the need to consider additional effects.

Findings

Correlation effects do not explain experimental discrepancies

Quantum Monte Carlo results differ from GW studies

Other effects like thermal disorder may be responsible

Abstract

Recent high resolution Compton scattering experiments in lithium have shown significant discrepancies with conventional band theoretical results. We present a pseudopotential quantum Monte Carlo study of electron-electron and electron-ion correlation effects on the momentum distribution of lithium. We compute the correlation correction to the valence Compton profiles obtained within Kohn-Sham density functional theory in the local density approximation and determine that electronic correlation does not account for the discrepancy with the experimental results. Our calculations lead do different conclusions than recent GW studies and indicate that other effects (thermal disorder, core-valence separation etc.) must be invoked to explain the discrepancy with experiments.