Towards a converged barrier height for the entrance channel transition state of the N(2D)Â +Â CH4 reaction and its implication for the chemistry in Titan's atmosphere

► Highly correlated ab initio methods confirm the existence of a potential barrier in the N(2D) + methane reaction. ► We suggest a barrier height of 3.86 ± 0.84 kJ/mol for the entrance transition state of the N(2D) + methane reaction. ► MS-MR-SDCI method corrected for SCE and BSSE has been used in present work.