A quotation often attributed to F. C. Frank goes along the lines of, “Crystals are like people — it’s the defects in them that make them interesting”. 2D materials, such as graphene, are no exception and adsorbates on graphene are known to affect many of its remarkable intrinsic properties. Furthermore, these adsorbed impurities can be electrically charged (so called “Coulomb” impurities) and their electronic and optical properties are not only interesting from a purely scientific perspective, but may have important implications for the development of future optoelectronic device technologies based on 2D materials.
As described in a pair of papers in 2D Materials and Physical Review B, we have developed a multi-scale theory of Coulomb impurities on graphene that combines large-scale density-functional theory calculations, continuum Thomas-Fermi theory and tight-binding models in a parameter-free framework that is able to predict and help interpret the most recent experimental measurements of individual adsorbates on graphene surfaces.
 F. Corsetti, A. A. Mostofi and J. Lischner, First-principles multiscale modelling of charged adsorbates on doped graphene, 2D Materials 4, 025070 (2017)
 D. Wong, F. Corsetti, Y. Wang, V. W. Brar, H.-Z. Tsai, Q. Wu, R. K. Kawakami, A. Zettl, A. A. Mostofi, J. Lischner and M. F. Crommie, Spatially resolving density-dependent screening around a single charged atom in graphene, Phys Rev B 95, 205419 (2017)