Ab initio study of energy loss and wake potential in the vicinity of a graphene monolayer

Abstract

A propagator of the dynamically screened Coulomb interaction in the vicinity of a graphene monolayer is calculated using ground-state Kohn-Sham orbitals, and the imaginary part of this propagator is used to calculate the energy-loss rate of a static blinking point charge due to excitation of electronic modes in graphene. Energy loss calculated for all (Q,ω) modes gives intensities of electronic excitations, including plasmon dispersions in graphene, with low-energy two-dimensional (2D) and high-energy π1, π2, and π + σ plasmons. Plasmon energies are in good agreement with experimental results. This spectral analysis also enables us to study the contribution of each plasmon mode to the stopping power and potential induced by a point charge moving parallel to the graphene. We find the bow waves that in pristine graphene appear for higher velocities (v >= 2vF) and predominantly originate from excitation of π plasmons. Doping induces extra features which appear for lower v≈vF velocities and predominantly originate from the excitation of 2D or Drude plasmons.