CALCULATION OF THE FUNDAMENTAL VIBRATIONAL FREQUENCIES AND INTENSITIES OF H-2, D-2, AND N-2 IN THE PRESENCE OF LI+ OR NA+

Self-consistent-field (SCF) and second-order Moller-Plesset (MP2) calculations, using large basis sets, have been carried out for the system X(2)...Y+, with X = H, D, and N and Y = Li and Na. In particular, the fundamental vibrational frequency shifts and intensities induced in the diatomic by the cation have been found. For Y = Na these properties may be compared with the experimental infrared spectra of the same diatomics when trapped in a NaA zeolite. There is good agreement between theory and experiment for the frequency shifts but the calculated intensity for N-2...Na+ is several times larger than that found in the zeolite. This indicates that either the model for the trapped species is too simple or the experimental result needs reassessment.