Ab initio computation of vibrational relaxation rate coefficients for the collisions of CO 2 with helium and neon atoms

Abstract

Ab initio calculations of rate coefficients are reported for the vibrational relaxation of CO 2 molecules in collision with helium and neon atoms. Self consistent-field computations have been performed to parameterise simple three-dimensional potential energy functions which have been used in vibrational close-coupling, rotational infinite-order-sudden calculations of rate coefficients. Excellent agreement is obtained between the calculated and experimental rate coefficients for the deactivation of the (01 10) vibrational level in the He + CO 2 system at temperatures of 300 K and above. The ab initio predictions of rate coefficients for relaxation of CO 2 vibrational levels such as (10 00) and (02 00) should be useful in computer simulations of CO 2 lasers.