Dicarbon Formation in Collisions of Two Carbon Atoms

Abstract

Radiative association cross sections and rates are computed, using a quantum approach, for the formation of C 2 molecules (dicarbon) during the collision of two ground-state C( 3 P ) atoms. We find that transitions originating in the C 1 Π g , d 3 Π g , and 1 5 Π u states are the main contributors to the process. The results are compared and contrasted with previous results obtained from a semiclassical approximation. New ab initio potential curves and transition dipole moment functions have been obtained for the present work using the multi-reference configuration interaction approach with the Davidson correction (MRCI+Q) and aug-cc-pCV5Z basis sets, substantially increasing the available molecular data on dicarbon. Applications of the current computations to various astrophysical environments and laboratory studies are briefly discussed, focusing on these rates.