Adsorption Site, Adsorption Energy, and Normal Vibration Frequency of H on Ni(100) via Total-Energy Calculations

Abstract

Density-functional total-energy calculations of H/Ni(100) show that the equilibrium H position is in the center site, $0.6a_0$ above the plane of the surface Ni atoms (with a Ni-H bond length of 1.8 Å). The bridge-site minimum lies only 0.1 eV higher than the center-site minimum, whereas the top-site minimum lies about 0.3 eV higher. This is consistent with a high hydrogen surface mobility.