Gas adsorption on a C60 monolayer.

The adsorption geometry of various gases on top of a C60 monolayer is investigated. The potential energy experienced by an adsorbate atom in the vicinity of a C60 molecule consists of Lennard-Jones interactions integrated over the spherical surface of the molecule. The adsorption potential exhibits strongly attractive sites which lead to a commensurate phase. The next adsorption sites are assumed on the basis of the symmetries of the triangular C60 array. The competition between different adsorption phases is solved by energy minimization. The onset pressure of each phase is computed and compared with experimental data for Kr on top of a C60 monolayer.