Viktor develops theoretical methods and computer programs for studying electronic structure, physical properties, and chemical reactions of molecules and solids. The focus of his research is on the Kohn-Sham density functional method, particularly on designing new density functional approximations in the form of model Kohn-Sham potentials. Applied computational research in his group centers on elucidating the mechanisms of chemical reactions, understanding the electronic structure of electrides, and unraveling the intricacies of chemical bonding in compounds under high pressure.