Structure determination of the p3×3R30∘ Bi-Ag(111) surface alloy using LEED I-V and DFT analyses

The deposition of 1/3 of a monolayer of Bi on Ag(111) leads to the formation of BiAg2 surface alloy with a long range ordered 3×3R30∘ superstructure. A detailed analysis of this structure using LEED I-V measurements together with DFT calculations is presented. We find strong correlation between experimental and calculated LEED I-V data, with the fit between the two data sets having a Pendry's reliability factor of 0.16. The Bi atom is found to replace one top layer Ag atom in each unit cell, forming a substitutional BiAg2 surface alloy, with the Bi atoms residing approximately 0.6 Å above the Ag atoms due to their size difference. DFT calculations are in good agreement with the LEED results.