Computational studies of interstellar silicon–nitrogen molecular species

Abstract

Ab initio and hybrid density functional theory (DFT) studies were performed in order to determine the stability of small silicon–nitrogen compounds. Results obtained with the highest level of ab initio studies currently available (the quadratic complete basis set, CBSQ) were used as a reference to compare results generated with other ab initio and DFT computational studies. The isomerization barriers, ionization potentials, electron affinities, and proton affinities for some of these molecular systems were computed. The values computed with CBSQ and hybrid DFT methods were in good agreement with each other. This suggests that these molecular species are more stable when hydrogen is attached to nitrogen which is contrary to carbon analogs which prefer hydrogen bound to the carbon atom. A comparison between DFT and high level ab initio values was used to determine the accuracy of DFT methods to evaluate silicon–nitrogen compounds.