Molecular Interactions with Many-Body Perturbation Theory.

Binding energies including valence-shell electron correlation were obtained from many-body perturbation theory MBPT for diborane, borane carbonyl, and borzane. Results were obtained for basis sets of double zeta quality and for basis sets with polarization functions added on all atoms. The binding energies were found to be respectively 35, 21, and 30 kcalmole. Correlation effects account for 48, 62, and 32 percent of the binding. The size-consistent nature of the MBPT method enables the computation of enthalpies of reaction for four different reactions involving monoborane, diborane, carbon monoxide, and borane carbonyl. When the theoretical values are corrected for vibrational zero-point energies and the experimental data are adjusted for temperature effects, the results agree within 5 percent and thus confirm the set of experimental enthalpies for the association reaction yielding diborane. The result for the binding energy of borazane constitutes a prediction in the absence of an experimental value. Author