A five-dimensional potential energy surface and predicted infrared spectra for the N2O-hydrogen complexes

We present a five-dimensional potential energy surface for the N2O-hydrogen complex using supermolecular approach with the full counterpoise correction at the coupled-cluster singles and doubles with noniterative inclusion of connected triple level. The normal mode Q(3) for the nu(3) antisymmetric stretching vibration of the N2O molecule was included in the calculations of the potential energies. The radial discrete variable representation/angular finite basis representation method and Lanczos algorithm were employed to calculate the rovibrational energy levels for four species of N2O-hydrogen complexes (N2O-para-H-2, -ortho-H-2, -ortho-D-2, and -para-D-2) without separating the inter- and intramolecular vibrations. The calculated band origins are all blueshifted relative to the isolated N2O molecule and in good agreement with the experimental values. The calculated rotational spectroscopic constants and molecular structures agree well with the available experimental results. The frequencies and line intensities of the rovibrational transitions in the nu(3) region of N2O for the van der Waals ground vibrational state were calculated and compared with the observed spectra. The predicted infrared spectra are consistent with the observed spectra and show that the N2O-H-2 complexes are mostly a-type transitions while both a-type and b-type transitions are significant for the N2O-D-2 complexes. (c) 2006 American Institute of Physics.