First-principles study of the Ni(111)(√3x√3)R30°-Pb surface

We apply first-principles calculations based on density function theory (DFT) within the generalized gradient approximation (GGA) to investigate Pb adsorption on and absorption in Ni(1 1 1)(root 3- x root 3-)R30 degrees surface. The adsorption energy calculations show that the substituional surface alloy without stacking fault is preferred, followed by on-surface hollow site adsorption, and the stacking faulted surface alloy is the most unstable. This confirms earlier experiments. The rumpling amplitude is calculated to be 0.987 angstrom. It broadly agrees with previous theoretical results and observations by low-energy electron diffraction (LEED) and medium-energy ion scattering (MEIS). but is much larger than that obtained by low-energy ion scattering. The work-function change due to Pb adsorption is found to be 0.433 eV, indicating the charge transfer from the substrate to the adsorbate. (c) 2006 Elsevier B.V. All rights reserved.