Inelastic partial cross sections for scattering of HF by neon

Abstract

An analytic expression of the potential energy surface (PES) of the ground state of the Ne-HF complex is obtained by utilizing nonlinear least square method to fit the intermolecular interaction energies [Zhang Y. Guizhou Science, 2003, 21(3): 9-13 (in Chinese)], which have been computed using the augmented correlation-consistent polarized quadruple zeta basis set aug-cc-pVQZ at the theoretical level of CCSD (T). On the basis of the PES, the partial cross sections (PCSs) at the incident energies of 60, 75, 100 and 150 meV for collisions between Ne atoms and HF molecules are calculated using the quantum close coupling approach. The effects of the long-range attractive and the short-range anisotropic interactions on the inelastic PCSs are discussed in detail. The results show: (1) The long-range attractive well of the EPS makes the significant contribution to the lower excitation PCSs, especially the tail maximum for j = 0→j′ = 1 transitions, whereas no contribution is to the j′≥3 inelastic transitions.(2) The short-range (the repulsive and attractive) interaction makes the significant contribution to the lower excitation PCSs, especially the main peak for j = 0→j′ = 1, 2. As for the transitions of j′≥3, the short-range interaction plays a key role in the inelastic excitation. (3) Although the positions of the maximums and minimums of the inelastic PCSs are different at the collision energies, they correspond to almost the same impact parameter. potential energy surface, inelastic partial cross section, close coupling approach Inelastic vibrational-rotational energy transfer in atomdiatomic molecule systems can provide a great deal of information for reference in practical processes, such as intramolecular vibrational predissociation [1] , gas phase relaxation [2] , predicting the laser action [3] and cooling of interstellar matter [4][5][6][7][8] , etc. Rare-gas-hydrogen-halide (Rg-HX) complexes have served as prototypes for studying both weakly intermolecular interaction and collision dynamics. Considerable attention has been paid, both by theory and experiment, to the interactions and scattering of the complexes [9][10][11][12][13][14][15] . In particular, Highresolution infrared spectra of Ne-HF were first reported by Nesbitt et al. [16] . The complex shows interesting dynamical features such as J-dependent predissociation rates, which allow the determination of a rigorous upper limit to the binding energy. In subsequent studies, the spectroscopy of the deuterated counterpart Ne-DF was investigated [17] . For Ne-DF, a richer spectroscopy was observed because of the smaller rotational constant of DF, which allows more bending excitation of the complex without predissociation. In parallel with the experimental efforts, ONeil et al. [18] constructed an ab initio potential energy surface (PES) using the correlated electron pair approximation (CEPA) and used it in rovibrational calculations. The agreement between the experimental results on Ne-HF and the theoretical predictions was reasonable. Lovejoy and Nesbitt...