A conventional way to tackle the problem from the computational viewpoint, now widely practiced, consists of the following. It is accepted that the chemical treatment implies mainly adsorption of different chemical units on the graphene surface. To describe the adsorption event computationally, one constructs a periodic supercell of graphene containing as many atoms as is necessary to comfortably accommodate the unit within the cell. Due to a large number of supercell atoms, an efœ- cient computational scheme, predominantly based on the density functional theory (DFT), is then applied. Usually, DFT schemes are limited by restricted approaches. Real progress is that not only restricted but also unrestricted DFT schemes are in operation. The latter are mainly aimed at considering magnetic properties of graphene ribbons, while adsorption still remains the object for restricted calculation schemes (look at two of the recent publications on the topic2,3).