Interaction Energies in a System of Three Organic Molecules Versus Their Structure and Mutual Induction

A method for the analysis of the interaction energies in a three-molecule nanocluster containing hydrocarbon molecules with double carbon–carbon bonds is presented. It is assumed that one of the molecules (pentene) has a dipole moment; the other two (aromatic molecules) have no dipole moments. The molecules in the considered three-molecule nanocluster are bounded by the long-range dispersion and induction interactions with the Coulomb repulsive forces at short intermolecular distances taken into account. Analytical expressions are obtained in terms of the presented method to calculate the dispersion and induction energies. In these expressions, the Coulomb repulsion at short distances is taken into account for each pair of molecules, which is possible owing to the specific charge properties of the double bonds in the considered molecules, which lead to the residual positive charges at the carbon atoms in these bonds. It was shown that the total interaction energy reached its minimum at smaller intermolecular distances between each pair of molecules compared with those in the corresponding isolated two-molecular nanocluster consisting of the same molecules.