The Nonregistered-Registered Phase Transition of Rare Gas Monolayers Adsorbed on Graphite. II

Abstract

As a continuation of the previous paper with the same title [J. Phys. Soc. Jpn. 46 (1979) 1852], a study is made again on the structure of rare gas monolayers physisorbed on graphite on the basis of a more realistic substrate potential. The two-dimensional sine-Gordon equation, which determines the equilibrium position of monolayer atoms with hexagonal modulation, is solved by a numerical variational method. The resulting free energy is compared to the monolayer with uniaxial mudulation. The present theory is shown to be equivalent to Novaco and McTague's theory in the limit of weak substrate potentials. Finally, a comparison is made also with the LEED and X-ray experiments on Kr and Ar monolayers, showing the present theory is in better agreement with the experiments than the previous paper.