LEED I–V and DFT structure determination of the Pb–Ag(111) surface alloy

Abstract

The deposition of 1/3 of a monolayer of Pb on Ag(111) leads to the formation ofPbAg2 surface alloy with a long range ordered superstructure. A detailed analysis of this structure using low-energy electron diffraction (LEED)I–V measurements together with density functional theory (DFT) calculations ispresented. We find strong correlation between experimental and calculated LEEDI–V data, with the fit between the two data sets having a Pendry’s reliability factor of 0.21. The Pbatom is found to replace one top layer Ag atom in each unit cell, forming a substitutionalPbAg2 surface alloy, as expected, with the Pb atoms residing approximately 0.4 Å above the Agatoms due to their size difference. DFT calculations are in good agreement with the LEEDresults.