Quantum Monte Carlo calculations of H$_2$ dissociation on Si(001)

TL;DR

This paper uses quantum Monte Carlo methods to accurately calculate H₂ dissociation on Si(001), providing improved reaction barriers that align closely with experimental data and highlighting the importance of coverage effects.

Contribution

The study applies quantum Monte Carlo to surface reactions, achieving more accurate reaction barriers and insights into coverage effects compared to previous computational approaches.

Findings

Reaction energies and barriers are higher than those from approximate functionals.

Adsorption barriers closely match experimental data.

Desorption barriers exceed current experimental values, emphasizing coverage effects.

Abstract

We present quantum Monte Carlo calculations for various reaction pathways of H$_2$ with Si(001), using large model clusters of the surface. We obtain reaction energies and energy barriers noticeably higher than those from approximate exchange-correlation functionals. In improvement over previous studies, our adsorption barriers closely agree with experimental data. For desorption, the calculations give barriers for conventional pathways in excess of the presently accepted experimental value, and pinpoint the role of coverage effects and desorption from steps.