The formation of urea in space. II. MP2 versus PM6 dynamics in determining bimolecular reaction products
In 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.
KeywordsReaction dynamics Astrochemistry Prebiotic chemistry Bimolecular collisions
We thank ANR DynBioReact (Grant No. ANR-14-CE06-0029-01) and CNRS program INFINITI (Project ASTROCOL) for financial support. This article is dedicated to the memory of Dr. János G. ÁNGYÁN, who directed the Ph. D. Thesis of one of us (YJ). We hope we will pass on the values and commitment we learned from him to those we work with and hopefully we will be able to do it with János’s humor and joy.
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