Diffusion Rates for Hydrogen on Pd(111) from Molecular Quantum Dynamics Calculations

TL;DR

This paper presents quantum mechanical calculations of hydrogen diffusion rates on Pd(111) surfaces using first-principles models, aligning well with experimental data when considering combined diffusion and friction effects.

Contribution

It introduces a quantum mechanical approach to compute hydrogen diffusion rates on Pd(111) using realistic models derived from first principles.

Findings

Results agree with experimental data for similar systems.

The total rate combines diffusion and friction contributions.

A kinetic model supports the interpretation of the diffusion rates.

Abstract

Diffusion rates are calculated on the basis of van Hove's formula for the dynamical structure factor (DSF) related to particle scattering at mobile adsorbates. The formula is evaluated quantum mechanically using eigenfunctions obtained from three dimensional realistic models for H/Pd(111) derived from first principle calculations. Results are compatible with experimental data for H/Ru(0001) and H/Pt(111), if one assumes that the total rate obtained from the DSF is the sum of a diffusion and a friction rate. A simple kinetic model to support this assumption is presented.