A determination of adatom–adatom interaction energies: Application to oxygen chemisorbed on the tungsten (110) surface

Abstract

A Monte Carlo simulation has been carried out to describe two-dimensional order–disorder phenomena. The model contains (attractive) first, (repulsive) second, and (attractive) third neighbor pairwise interactions. The special case of oxygen chemisorption on a tungsten (110) surface, on which an ordered p (2×1) overlayer is formed at low surface temperatures, is considered explicitly. From the measured order–disorder transition temperatures at both quarter- and half-monolayer surface coverages, (nonunique) values of the three pairwise interaction energies have been determined. These pairwise interaction energies have been used to determine the variation in the total interaction energy, the heat capacity and the entropy with surface temperature.