Density functional theory screened-exchange approach for investigating electronical properties of graphene-related materials

We present ab initio calculations of the band structure of graphene and of short zigzag graphene nanoribbons (ZGNRs) by the screened-exchange-local-density approximation (LDA) method within the framework of density functional theory. The inclusion of nonlocal electron-electron interactions in this approach results in a renormalization of the electronic band structure and the Fermi velocity compared to calculations within LDA gives good agreement with experiment. Similarly, the band gaps in ZGNRs are widened by more than 200%, being of similar magnitude than band gaps from past studies based on quasiparticle band structures. We found a noticeable effect of nonlocal exchange on the spin polarization of the electronic ground state of ZGNRs, compared to LDA and generalized gradient approximation calculations.