Theory of the W(100) surface reconstruction and hydrogen adsorption effects

The reconstruction of the W(100) surface and the H adsorption effects are discussed on the phenomenological model combined with the lattice gas model for the adsorbed H where couplings are assumed between the displacements of the surface W atoms and between the displacements and the adsorbed H. Analyses are made by computer simulation. The present model for the clean surface, which is an extension of the two-dimensional XY model, is found to be also nonuniversal. At low coverages of the adsorbed H, the directional transition of displacements of the surface W atoms is found to be gradual, and a possibility of the adsorbed H condensation is pointed out