Finite temperature quantum distribution of hydrogen adsorbate on nickel (0 0 1) surface

Finite temperature quantum behavior of hydrogen and deuterium adsorbates on Ni(0 0 1) surface has been simulated using path-integral Monte Carlo technique. The adsorbate-surface interaction is described by the many-body alloy potential form, fitted to the adsorption parameters from DFT calculations. This allows consideration of substrate atom dynamics. Temperatures 100 K and 300 K have been considered and contribution of the thermal motion of Ni surface atoms is analyzed.At low temperatures the quantum delocalization of the adsorbate is considerable, and therefore, temperature dependence of distributions is weak. In this case, the isotope effect is larger. At higher temperatures, however, the thermal dynamics of the substrate dominates all studied phenomena and classical description may be sufficient. By using a semi-classical description of the hydrogen adsorbate temperature dependence of the distributions and energetics becomes strong at all temperatures, providing that quantum description is necessary for the correct picture of H/Ni(0 0 1) system.