Ab initio treatment of charge transfer in CS + molecular system

Abstract

The charge transfer process C +(2s 22p) 2P + S(3s 23p 4) 3P → C(2s 22p 2) 3P + S +(3s 23p 3) 4S is important in the modellisation of the interstellar medium chemistry. The rate constant generally used in the astrochemical models for the C + + S → C + S + reaction is 1.5 × 10 −9 cm 3 s −1 [1] between 10 K and 41 000 K, but it remains uncertain for such a large domain of temperature. Since no precise calculation has been ever performed for this process, we have undertaken the first complete ab initio molecular treatment of this collision, followed by a semi-classical dynamics. The results suggest that the rate constant adopted in astrochemical models might be overestimated.