Analytic Morse/long-range potential energy surfaces and predicted infrared spectra for CO-H-2 dimer and frequency shifts of CO in (para-H-2)(N) N=1-20 clusters

作者：Li, Hui^*; Zhang, Xiao-Long; Le Roy, Robert J.; Roy, Pierre-Nicholas

来源：Journal of Chemical Physics, 2013, 139(16): 164315.

DOI：10.1063/1.4826595

• DER-WAALS COMPLEXES
• SEEDED HYDROGEN CLUSTERS
• WEAKLY-BOUND COMPLEX
• CARBONYL SULFIDE
• GROUND-STATE
• VIBRATIONAL-RELAXATION
• LASER SPECTROSCOPY
• COLLISIONS
• MOLECULES
• H-2

A five-dimensional ab initio potential energy surface (PES) for CO-H-2 that explicitly incorporates dependence on the stretch coordinate of the CO monomer has been calculated. Analytic four-dimensional PESs are obtained by least-squares fitting vibrationally averaged interaction energies for v(CO)=0 and 1 to the Morse/long-range potential function form. These fits to 30 206 points have root-mean-square (RMS) deviations of 0.087 and 0.082 cm(-1), and require only 196 parameters. The resulting vibrationally averaged PESs provide good representations of the experimental infrared data: for infrared transitions of paraH(2)-CO and orthoH(2)-CO, the RMS discrepancies are only 0.007 and 0.023 cm(-1), which are almost in the same accuracy as those values of 0.010 and 0.018 cm(-1) obtained from full six-dimensional ab initio PESs of V-12 [P. Jankowski, A. R. W. McKellar, and K. Szalewicz, Science 336, 1147 (2012)]. The calculated infrared band origin shift associated with the fundamental of CO is -0.179 cm(-1) for paraH(2)-CO, which is the same value as that extrapolated experimental value, and slightly better than the value of -0.176 cm(-1) obtained from V-12 PESs. With these potentials, the path integral Monte Carlo algorithm and a first order perturbation theory estimate are used to simulate the CO vibrational band origin frequency shifts of CO in (paraH(2))N-CO clusters for N = 1-20. The predicted vibrational frequency shifts are in excellent agreement with available experimental observations. Comparisons are also made between these model potentials.

• 出版日期2013-10-28
• 单位吉林大学