Density Functional Theory Study of the Interaction of Magnesium Ions with Graphene Chip

Abstract

The interaction of magnesium atom (Mg) and ionic species (Mg+ and Mg2+) with graphene chip (finite sized graphene) have been investigated by means of density functional theory (DFT) method. The B3LYP/6-31G(d) calculation showed that the Mg atom does not make a chemical bind to the graphene chip. On the other hand, the ionic species can bind srongly to a hexagonal site of graphene chip. Time-dependent (TD)-DFT calculation of Mg+ doped graphene showed that the first excitation band is assigned to a charge transfer band from a π-orbital of graphene chip (HOMO: highest occupied molecular orbital) to a singly occupied molecular orbital (SOMO) composed of Mg+(3s) orbital, whereas the second excitation band is composed of a π–π* transition corresponding to the HOMO–lowest unoccupied molecular orbital (LUMO) excitation of free graphene chip. The nature of the interaction between the Mg ions and the graphene chip was discussed on the basis of theoretical results.