First-principles density-functional calculations of H adsorption on the (001) surface were performed. Good agreement was found with experimental data on the adsorption energy, binding distance, and barrier height for diffusion at room temperature. A model potential was fitted to the first-principles data points by using the simulated annealing technique, and the H band structure was derived by solving the 3-dimensional Schrödinger equation. The vibrational excitation energies were found to be slightly too high, by about 10%, as compared with experiment; with very narrow H bands. The experimentally observed absence of a marked isotope effect for H diffusion at low temperatures was explained in terms of tunnelling in a static 3-dimensional potential.

Quantum-Mechanical Calculation of H on Ni(001) using a Model Potential Based on First-Principles Calculations. T.R.Mattsson, G.Wahnström, L.Bengtsson, B.Hammer: Physical Review B, 1997, 56[4], 2258-66