Theory of orientational epitaxy in the self-consistent phonon approximation

Abstract

The theory of the orientational epitaxy phase is developed for an anharmonic solid monolayer within the framework of a self-consistent phonon approximation. This theory shows how the adatom-adatom coupling constants and adatom-substrate coupling constants in the theory of Novaco and McTague are modified by renormalization due to the zero-point motion and the thermal vibration of the adatoms. Some general conclusions about the nature of orientational epitaxy are presented and numerical results are given for argon adsorbed on basal plane graphite. These results show that while many calculated properties of the argon solid have important corrections due to the anharmonic nature of the system, the orientation angle versus lattice constant curve is not affected to any significant degree.