We suggest a physical picture of the catalytic act combining together the energy transfer and the synchronisation of the best electron density in the reactant and active site as a consecutive sequence of events. Activity and selectivity at molecular level are defined. Geometry requirements seem to be linked to energy and time requirements. Our proposal for developing new catalysts at the molecular level is to find the set of most profitable ranges of frequencies of the vibrators in an ideal catalytic system, predicted by combination of the SET and IOM models. In order to transform these results to a practical catalyst one can use quantum chemistry computation to characterise vibration modes of real systems for a wide range of variations. The shifts of the frequencies resulted from comparison of the calculated with the SET and IOM models frequencies and ones for non-interacting reactant and catalytic centre can serve as the base data in choice of the real systems. If, for one such system, the quantum chemistry calculated frequencies agree with the ones predicted from SET and IOM, a good catalyst is found.