Rotational cross sections and rate coefficients fore-CO ande-HCN collisions under interstellar conditions

Rotational cross sections and rate coefficients for $e$-CO and $e$-HCN collisions have been calculated in the energy range relevant to dark interstellar clouds by using the close-coupling method. Gordon's technique has been used for solving the coupled Schrödinger equations. Initial rotational levels $j=0, 1, \mathrm{and} 2$ of CO and HCN have been considered. The rotational cross sections have been calculated in the energy range 0.0006 to 0.1 eV and the rate coefficients in the temperature range 5-100 K. The cross sections and rate coefficients thus obtained have been compared with Born and unitarized time-dependent perturbation calculations.