Density functional theory study of phonons in graphene doped with Li, Ca and Ba

Vibrational frequencies and phonon displacement patterns of the H-site doped graphene are calculated by the density functional theory (DFT). DFT calculations, as well as the group theory study, are used to describe these structures as interesting materials for single layer superconductivity. In this paper, graphene doped with Li, Ca and Ba adatoms is systematically analysed and compared. Due to the effect of zone folding, displacement patterns of calculated modes correspond to the ones of the K and Γ point phonons of graphene and this offers the possibility for comparison with the experimental results for graphene. Our objective was to provide compendious and practical guidelines for the experimental research and characterization of these structures.