THE INFRARED-SPECTRUM OF THE METHYLIDYNE-PHOSPHINE DIMER, (HCP)2

In this paper, we report ab initio geometries, infrared frequencies and intensities for the HCP dimer. Two levels of theory have been used, restricted Hartree-Fock (RHF) and Moller-Plesset second-order perturbation theory (MP2). Significant reduction of the intermolecular distance is found between the RHF and MP2 optimizations. At the MP2 level, only one dimer, the "T" shaped, is found to be a minimum. The infrared frequencies and intensities exhibit the typical characteristics of a weakly interacting system, which along with the MP2 zero-point dissociation energy of -3.5 kJ mol-1, classes this dimer as a van der Waals complex.