A model of a surface dimer in the problem of adsorption

—The adsorption system has been represented in a form of two regions: a dimer, which includes the ad particle and substrate surface atom, and the rest of the space. Metal, semiconductor, and graphene (semimetal) have been considered as a substrate. The similarities and differences in the values of the ad particle occupation numbers that have been obtained in the framework of the proposed and standard adsorption models have been discussed.