Plasmon excitations in free-standing graphene and graphene/hexagonal boron nitride (hBN) heterostructure are studied using linear-response time-dependent density functional theory within the random phase approximation. Within a single theoretical framework, we examine both the plasmon dispersion behavior and lifetime (line width) of Dirac and π plasmons on an equal footing. Particular attention is paid to the influence of the hBN substrate and the anisotropic effect. Furthermore, a model-based analysis indicates that the correct dispersion behavior of π plasmons should be ωπ(q)=Eg2+βq for small q's, where Eg is the band gap at the M point in the Brillouin zone, and β is a fitting parameter. This model is radically different from previous proposals, but in good agreement with our calculated results from first principles.
@article{arxiv.1706.07200,
title = {First-principles calculations and model analysis of plasmon excitations in graphene},
author = {Pengfi Li and Xinguo Ren and Lixin He},
journal= {arXiv preprint arXiv:1706.07200},
year = {2017}
}