Nonadditive interactions in the H2 trimer

Explicit equations for the second order nonadditive induction energy for interactions involving three linear molecules have been derived using the MAPLE symbolic computational language. This nonadditive induction energy (involving the permanent quadrupole moments and dipole polarizabilities) is compared with the triple-dipole dispersion energy for a system consisting of three hydrogen molecules, in two different configurations. It is found that for most of the orientations studied the nonadditive induction energy is comparable in magnitude or larger than the triple-dipole dispersion energy.