Revealing the nature of intermolecular interaction and configurational preference of the nonpolar molecular dimers (H2)2, (N2)2, and (H2)(N2)

Understanding the nature of noncovalent interactions between nonpolar small molecules is not only theoretically interesting but also important for practical purposes. The interaction mechanism of three prototype dimers (H-2)(2), (N-2)(2), and (H-2)(N-2) are investigated by state-of-the-art quantum chemistry calculations and energy decomposition analysis. It is shown that their configuration preferences are essentially controlled by the electrostatic component rather than the dispersion effect though the monomers have zero dipole moment. These configuration preferences can also be fairly well and conveniently interpreted by visually examining the electrostatic potential map.