Adsorption of para-hydrogen on krypton pre-plated graphite

Adsorption of para-hydrogen on the surface of graphite pre-plated with a single atomic layer of krypton, is studied theoretically by means of path integral ground state Monte Carlo simulations. We compute energetics and density profiles of para-hydrogen, and determine the structure of the adsorbed film for various coverages. Results show that there are two thermodynamically stable monolayer phases of p-H2, both solid; one is commensurate with the krypton layer, and has coverage θ ≈ 0.0636 Å−2; the other is incommensurate, has coverage θ ≈ 0.0716 Å−2, and is compressible up to θ ≈ 0.0769 Å−2. No evidence is observed of a liquid phase at T=0 for intermediate coverages. These results are qualitatively similar to what is seen for p-H2 on bare graphite. Quantum exchanges of hydrogen molecules are suppressed in this system.