Quantum calculations of inelastic scattering of HCN and HNC by Ar

A quantum scattering calculation of collision cross-sections and energy transfer of HCN and HNC in collisions with Ar is reported. The HCN (HNC) rotation is treated in the infinite order sudden approximation, and the HCN (HNC) vibrations are treated by the coupled-channel method. A sum of two-body Lennard-Jones potentials is used to describe the Ar-HCN/HNC interaction, and the HCN/HNC intramolecular potential is a global fit to extensive, high quality ab initio calculations. Vibrational state-to-state cross-sections and state specific energy transfer for HCN and HNC states are calculated as functions of initial relative translational energy.