A new methodology to describe the interactions in "receptor-ligand" complexes is presented. The methodology is based on a combination of the 3D/4D QSAR BiS/MC and CoCon algorithms. The first algorithm performs the restricted docking of compounds to receptor pockets. The second determines the relationships between the bioactivity and the parameters of interactions in the "receptor-ligand" complexes, including a new formalism for estimating hydrogen bond energies.