▎ 摘　　要

A theoretical scheme of calculating the density of states and the occupation number of an adatom has been proposed. Two limiting cases of coupling in the adatom-single-layer graphene-substrate adsorption system have been considered in terms of the perturbation theory: the cases of strong and weak couplings of graphene with the substrate. The effect of metallic and semiconductor substrates on the electronic state of an adatom has been studied using simple models. It has been shown that, in all the considered cases, the firstorder perturbation theory corrections decrease the occupation number of an adatom.