Strain effect on the electronic spectrum of graphene: beyond two-dimensionality

We study the dependence of the plasmon dispersion relation of graphene on applied uniaxial strain. Besides electron correlation at the random-phase approximation level, we also include local field effects specific for the honeycomb lattice. As a consequence of the two-band character of the electronic band structure, we find two distinct plasmon branches. We recover the square-root behavior of the low-energy branch, and find a nonmonotonic dependence of the strain-induced modification of its stiffness, as a function of the wave-vector orientation with respect to applied strain. We also take into account the full three-dimensional representation for the wave functions of single-particle excitations. This induces quantitative changes in the plasmon dispersion relation.