The formation of urea in space. II. MP2 versus PM6 dynamics in determining bimolecular reaction products

International audienceIn the present work, we have investigated the possibility of forming protonated urea in the gas phase by means of chemical dynamics simulations. Based on previously published highly correlated quantum chemistry calculations (Astron. Astrophys. 610, A26, 2018), we have considered the reaction between the high energy tautomer of protonated hydroxylamine (NH2OH2 +) and neutral formamide. Simulations were made at MP2 level and using three semi-empirical Hamiltonians which allow better statistics. In particular we have considered the PM6 method and two different dispersion corrections. These more approximated methods show results which are in relatively good agreement with MP2, in particular for the reaction which is potentially responsible for the urea synthesis. Results show that precursor of protonated urea can be formed but this species will evolve with difficulty into the structure of urea in ultra-vacuum conditions. It is likely that the presence of mantle ice would facilitate the overall reaction process