ab-Initio and DFT study of HCN: Role of temperature for the formation of HCN molecule in the interstellar medium

•Computational studies for the formation of Hydrogen Cyanide (HCN) molecule in interstellar medium.•Effect of temperature on Enthalpy, Entropy and Gibbs free energy of HCN molecule.•Formation of HCN through hydrogenation of CN radical.•Proposed Reaction paths are highly feasible in interstellar medium.•Feasibility of reaction mechanism has been also confirmed by calculating Rate coefficient.•This work has been studied with HF and DFT (at different functionals, viz. B3LYP, B3PW91 & WB97XD) methods using 6-31G++(d,p) basis set by Gaussian 09 software.