First-principles study on field evaporation of surface atoms from W(011) and Mo(011) surfaces

TL;DR

This study uses first-principles simulations to investigate the electric field-induced evaporation of surface atoms from tungsten and molybdenum surfaces, revealing that local field enhancement occurs above atoms rather than around them, challenging classical assumptions.

Contribution

It provides a first-principles analysis of field evaporation, showing that local-field enhancement occurs above atoms and aligning threshold fields with experimental data.

Findings

Threshold electric fields match experimental values

Local field enhancement occurs above atoms, not around

Field strength is lower than classical predictions

Abstract

The simulations of field-evaporation processes for surface atoms on W(011) and Mo(011) surfaces are implemented using first-principles calculations based on the real-space finite-difference method. The threshold values of the external electric field for evaporation of the surface atoms, which are $\sim$ 6 V/\AA 2mm for tungsten and $\sim$ 5 V/\AA 2mm for molybdenum, are in agreement with the experimental results. Whereas field evaporation has been believed to occur as a result of significant local-field enhancement around the evaporating atoms, in this study, the enhancement is not observed around the atoms but above them and the strength of the local field is much smaller than that expected on the basis of the classical model.