Core-level shifts for surface bimetallic systems from first-principles theory: Pd-Mn structures on Pd(100)

The surface core-level shift (SCLS) for Pd(100) and Mn-induced Pd core-level shifts (CLSs) for PdMn surface alloys with different configurations formed on Pd(100) are calculated from first-principles theory. The shifts are calculated within the complete screening picture, which includes initial (core-electron energy-eigenvalue) and final state (relaxation due to screening) effects in the same scheme. The theoretical results are compared to recent experimental results for 1 monolayer Mn/Pd(100), formed at low temperature, and the ordered Pd(100)-c(2×2)-Mn surface alloy formed upon annealing. The calculated core-level shifts are in all cases in good agreement with the experimental values. It is furthermore shown that the Pd(100)-c(2×2)-Mn surface alloy as prepared experimentally is metastable, and predictions are made on the CLSs for energetically more stable structures that could be reached with further annealing.