▎ 摘　　要

Several polycyclic aromatic hydrocarbons (PAHs) were studied as finite size models of graphene and graphene nanoribbons using density functional theory. Continuous electron density, molecular electrostatic potential (MEP) and MEP-derived net charge distributions in these systems were analyzed. It is found that the edges of all the PAHs studied are associated with appreciably enhanced electron density in comparison to their other parts. Internal edges created by removing carbon atoms of an inner benzene ring followed by attachment of hydrogens to carbon atoms with unsatisfied valencies are also found to be associated with enhanced electron density. Experimental observations reported on graphene and GNRs showing enhanced reactivity of their edges can be explained on the basis of the enhanced electron density edge effect found in the PAHs.