Structures and Properties of Known and Postulated Interstellar Cations
arXiv:2107.11122 · doi:10.3847/1538-4365/ac194c
Abstract
Positive ions play a fundamental role in the interstellar chemistry, especially in cold environments where chemistry is believed to be mainly ion-driven. However, in contrast with neutral species, most of the cations present in the astrochemical reaction networks are not fully characterized in the astrochemical literature. To fill up this gap, we have carried out new accurate quantum chemical calculations to identify the structures and energies of 262 cations with up to 14 atoms that are postulated to have a role in the interstellar chemistry. Optimised structures and rotational constants were obtained at M06-2X/cc-pVTZ level, while electric dipoles and total electronic energies were computed with CCSD(T)/aug-cc-pVTZ//M06-2X/cc-pVTZ single point energy calculations. The present work complements the study by Woon & Herbst (2009), who characterised the structure and energies of 200 neutral species involved as well in the interstellar chemistry. Taken together, the two datasets can be used to estimate whether a reaction, postulated in present astrochemical reaction networks, is feasible from a thermochemistry point of view and, consequently, to improve the reliability of the present networks used to simulate the interstellar chemistry. We provide an actual example of the potential use of the cations plus neutral datasets. It shows that two reactions, involving Si-bearing ions and present in the widely used reaction networks KIDA and UMIST, cannot occur in cold ISM because endothermic.
References in corpus (7)
- A KInetic Database for Astrochemistry (KIDA)
- A line confusion limited millimeter survey of Orion KL. II: Silicon-bearing species
- Space and laboratory discovery of HC3S+
- Silicon-bearing molecules in the shock L1157-B1: first detection of SiS around a Sun-like protostar
- Discovery of the acetyl cation, CH3CO+, in space and in the laboratory
- Reactions forming C(0,+)n=2,10, Cn=2,4H(0,+) and C3H(0,+) in the gas phase: semi empirical branching ratios
- Formation and destruction of SiS in space