The effect of middle range forces on the rate constant of a fast chemical reaction within adiabatic capture theory Original Research Article

We study the reaction between a proton and a linear molecule within adiabatic capture theory. A comparison is made between capture rate constant calculations using a density functional theory (DFT) potential including correlation polarisation contributions and those involving only the asymptotic form of the interaction potential. We find that the long range analytical form of the static potential is in close agreement with the DFT potential up to short intermolecular distances. Conversely the range of validity of the analytical correlation polarisation potential appears to be not as large. The temperature dependence of the rate constant is found to be steepen when using the DFT potential. Various examples are considered of importance to interstellar chemistry, including the reactions p + CO2, p + NO and P + C2H2.