AB-INITIO POTENTIAL-ENERGY SURFACE AND INFRARED-SPECTRUM OF THE NE-COCOMPLEX

Symmetry-adapted perturbation theory has been applied to compute the i ntermolecular potential energy surface of the Ne-CO complex. The inter action energy is found to be dominated by the first-order exchange con tribution and the dispersion energy. The ab initio potential has a sin gle minimum of epsilon(m) = -53.39 cm(-1) at R-m = 6.34 bohr and theta (m) = 92.2 degrees. The computed potential energy surface has been ana lytically fitted and used in converged variational calculations to gen erate bound rovibrational states of the Ne-20-CO complex and the infra red spectrum corresponding to the simultaneous excitation of vibration and internal rotation in the CO subunit within the complex. The compu ted frequencies of the infrared transitions corresponding to the Sigma --> Sigma, Sigma --> Pi, and Pi --> Sigma subbands are in good agreem ent with the experimental data (Randall, R. W., et al. Mol. Phys. 1993 , 79, 1113). The observed bending combination band is assigned to the transitions from the ground state to the first excited Sigma state. Fr equencies of the Pi --> Delta and Delta --> Pi transitions which were observed in the static cell spectrum are also reported.