▎ 摘　　要

The functionalization of graphene with transition metals is of great interest due to its wide range of applications, such as hydrogen storage, spintronics, information storage, etc. Due to its magnetic property adsorption of Mn atom on graphene has a high consequence on the electronic properties of graphene. The increase in size of the graphene sheet with hydrogen termination has a high impact on the transformation of electronic properties of the graphene sheet. Hence in this work, we investigate the size as well as change in structural and electronic properties of pristine/defective graphene sheets on adsorption of Mn atom using density functional theory methods. From the results obtained a higher adsorption energy value of 3.04 eV is found for Mn adatom on the defected graphene sheet than the pristine, 1.85 eV. It is subject to the coverage effect which decreases on increasing number of carbon atoms. Moreover, a decrease in energy gap is observed in pristine and defected graphene sheets with a high number of carbon atoms. The density of states illustrates the significant effect for hydrogen termination in the conduction band of the Mn adsorbed graphene sheet with low carbon atoms.