Ab initio determination of the infrared phosphine torsion spectrum in vinylphosphine with ZPE correction

The potential energy curve for the hindered internal rotation of the phosph ine group in vinylphosphine is determined at MP2 and MP4 levels with a 6-31 1G(3df,p) basis set, and the vibrational zero point energy correction. From the optimal geometries of each conformation the kinetic parameter is calcu lated as a function of the rotation angle. By solving the Schrodinger equat ion for the internal rotation, the torsional levels and torsional wave func tions are obtained. From these results and the electric dipole moment varia tions, Be torsional spectrum in the far infrared is synthesized. A c-type b and progression for the syn-syn transitions is encountered. This result agr ees fairly well with those obtained for ethylphosphine, the spectrum of whi ch is well known. (C) 2000 John Wiley & Sons, Inc.