Rotationally inelastic scattering of OH((2)Pi) by HCl((1)Sigma). Comparison of experiment and theory

State-to-state integral cross sections were calculated using quantum open-shell and closed shell close coupling scattering calculations and quasi-classical trajectory calculations. Reduced dimensionality calculations for the OH-HCl system are compared to those for the OH-Ar system. We have explored the sensitivity of the cross section to the nature of the PES, using either a two-dimensional or a four-dimensional PES. Only the diagonal diabatic V-sum potential was used in the calculations and therefore the electronic fine structure, i.e. the spin-orbit and Lambda-doublet structure, could not be accounted for. All the calculations were performed for the same collision energy of 920 cm(-1) and assuming that initially all OH molecules are in the lowest rotational state, J=3/2, Omega=3/2. The theoretical results are discussed in comparison with the experimental data measured under similar conditions. The agreement of experimental results with the theoretical model based on four-dimensional close coupling calculations and treating the OH molecule as a closed-shell species is good. The validity of different proposed correspondence schemes for the transitions in OH considered as a closed-shell and as an open-shell molecule is examined by comparing the cross sections obtained for the OH+Ar system and the two-dimensional model for the OH+HCl system.