Tight-binding model study of the evolution of G-peak in Monolayer graphene

We propose here a tight-binding model with nearest-neighbor hopping integral in presence of one site doping. Phonon is coupled to the hopping integral with dimensionless coupling g in presence of bare phonon vibrational energy in graphene plane. Phonon Green's function D-q,D-q(omega) is calculated from the total Hamiltonian by using Zubarev's Green's function technique and the phonon self-energy is evaluated from the pure electronic Hamiltonian. The Raman spectral density function (SDF) is calculated from the formula SDF = -2 pi lm[D-q,D-q (omega + i eta)] , where eta is the small spectral width. The calculated Raman spectra exhibits high energy and highly intense G peak, phonon momentum transfer energy peak and a lower energy anomalous peak. The evolution of these peaks is investigated by varying the model parameters of the graphene system.