Theoretical study of modified electron band dispersion and density of states due to high frequency phonons in graphene-on-substrates

Abstract

We propose here a theoretical model for the study of band gap opening in graphene-on-polarizable substrate taking the effect of electron-electron and electron-phonon (EP) interactions at high frequency phonon vibrations. The Hamiltonian consists of hopping of electrons upto third nearest-neighbors and the effect substrate, where A sublattice site is raised by energy + ? and B sublattice site is suppressed by energy-?, hence producing a band gap energy of 2?. Further, we have considered Hubbard type electron-electron repulsive interactions at A and B sublattices, which are considered within Hartree-Fock meanfield approximation. The electrons in the graphene plane interact with the phonon's present in the polarized substrate in the presence of phonon vibrational energy within harmonic approximation. The temperature-dependent electron occupancies are computed numerically and self-consistently for both spins at both the sublattice sites. By using these electron occupancies, we have calculated the electron band dispersion and density of states (DOS), which are studied for the effects of EP interaction, high phonon frequency, Coulomb energy and substrate induced gap. � 2018 World Scientific Publishing Europe Ltd.