A Combined DFT and RRKM-Based Study on the Reactivity of HCO + NH$$:2$$ on Amorphous Water Ice Surface

Abstract

Formamide is observed in the interstellar medium and it is thought to play an important role as a precursor of prebiotic molecules. In this work we study the reactivity of NH and HCO on the open surface of amorphous ice model, which can either lead to the formation of formamide (through radical-radical coupling) or CO + NH (through direct H-abstraction) by means of DFT electronic structure calculations, and derive their unimolecular rate constants within the RRKM scheme. We found that radical-radical coupling is faster and hence there is no competition between the two processes in this particular case. Despite of this result, the radical-radical mechanism in dust grain ices is still to be validated.