Abstract:
Using first principles methods, we study the mechanical properties of monolayer and bilayer graphene with 50%
and 100% coverage of hydrogen. We employ the vdW-DF, vdW-DF-C09x and vdW-DF2-C09x van der Waals
functionals for the exchange correlation interactions that give significantly improved interlayer spacings and
energies. We also use the PBE form for the generalized gradient corrected exchange correlation functional for
comparison. We present a consistent theoretical framework for the in-plane layer modulus and the out-of-plane
interlayer modulus and we calculate, for the first time, these properties for these systems. This gives a measure
of the change of the strength properties when monolayer and bilayer graphene are hydrogenated. As well as
comparing the relative performance of these functionals in describing hydrogenated bilayered graphenes, we
also benchmark these functionals in how they calculate the properties of graphite.
