Second layer of H2 and D2 adsorbed on graphene

TL;DR

This study uses diffusion Monte Carlo calculations to analyze the phase diagrams of para-H2 and ortho-D2 on graphene, revealing the nature of their second-layer structures and comparing favorably with experimental data.

Contribution

It provides detailed theoretical insights into the second-layer phase behavior of H2 and D2 on graphene, a topic not extensively covered before.

Findings

Second layer forms a triangular incommensurate solid.

Densities for layer promotion match experimental data.

Results support the understanding of quantum adsorption phenomena.

Abstract

We report diffusion Monte Carlo calculations on the phase diagrams of para-H2 and ortho-D2 adsorbed on top of a first layer of the same substances on graphene. We found that the ground state of the second layer is a triangular incommensurate solid for both isotopes. The densities for promotion to a second layer and for the onset of a two-dimensional solid on that second layer compare favorably to available experimental data in both cases.