Watching hydrogen interaction with graphene: an ab initio molecular dynamics study using embedded mean-field theory

Reaction of H atoms with graphene-like surfaces is fundamental for interstellar research, hydrogen storage, and graphene-based spintronics. Ab initio molecular dynamics (AIMD) simulations can play an important role in obtaining detailed, dynamical understanding of this process. However, this simple system poses significant challenges for current theoretical approaches. For example, different electronic structure methods predict distinct adsorption barriers; nuclear quantum effects are important and should be included in the simulations; large size of the graphene system is required to capture the phonon bending and conformational fluctuations; necessary inclusion of exact exchange interactions and the use of large system size make the standard AIMD simulations prohibitively expensive. Here, we present AIMD simulations of H-atom reactive scattering using the embedded mean-field theory (EMFT), which allows for on-the-fly ab initio calculations of the energy and forces with hybrid-DFT accuracy but at the much lower cost of LDA level. Nuclear quantum effects are also accounted for by combining EMFT with the path-integral-based ring-polymer molecular dynamics method. Our simulation results have shown to give excellent agreement with experimental results obtained by the Wodtke group.