Surface stress of Ni adlayers on W(110): the critical role of the surface atomic structure

TL;DR

This study uses density functional theory to analyze how the atomic structure of Ni adlayers on W(110) influences surface stress, revealing that changes in Ni adsorption sites are key to understanding experimental stress trends.

Contribution

It provides a new atomic structure model for the 1x7 phase and explains the surface stress behavior based on atomic site changes, advancing understanding of surface stress phenomena.

Findings

Predicted a more regular atomic structure for the 1x7 phase.

Reproduced the experimental surface stress change without density variation.

Identified Ni adsorption site changes as the main factor affecting surface stress.

Abstract

Puzzling trends in surface stress were reported experimentally for Ni/W(110) as a function of Ni coverage. In order to explain this behavior, we have performed a density-functional-theory study of the surface stress and atomic structure of the pseudomorphic and of several different possible 1x7 configurations for this system. For the 1x7 phase, we predict a different, more regular atomic structure than previously proposed based on surface x-ray diffraction. At the same time, we reproduce the unexpected experimental change of surface stress between the pseudomorphic and 1x7 configuration along the crystallographic surface direction which does not undergo density changes. We show that the observed behavior in the surface stress is dominated by the effect of a change in Ni adsorption/coordination sites on the W(110) surface.