▎ 摘　　要

Direct molecular orbital-molecular dynamics (MO-MD) method has been applied to diffusion processes of the Li+ ion on a modified graphene surface. A graphene sheet composed of carbon, fluorine and hydrogen atoms were used as a model graphene (Li+C150H3F27, denoted by FH-graphene). The edges of graphene were terminated by fluorine (F-edge region) and hydrogen atom (H-edge region). Simulation temperatures were chosen in the range 250-350 K. It was found that the lithium ion diffuses freely on the surface, but the ion does not approach the F-edge region of the surface. This is due to the repulsive interaction with a positive charged carbon atom where C-F bond is polarized as C delta+-F delta-. On the other hand, the Li+ ion approached to the H-edge region and it exited from the H-edge region. The diffusion mechanism of Li-was discussed on the basis of theoretical results. (C) 2010 The Japan Society of Applied Physics