# The GRETOBAPE gas-phase reaction network: the importance of being exothermic

## TL;DR

The paper introduces GRETOBAPE, a revised gas-phase reaction network for astrochemistry, emphasizing the importance of verifying reaction exothermicity through quantum calculations to improve model accuracy.

## Contribution

It presents a new astrochemical reaction network, GRETOBAPE, with all reactions checked for exothermicity using quantum mechanics, and provides a reduced version for specific astrochemical applications.

## Key findings

- 5% of reactions in the original network are endothermic
- The Si-bearing species network is most affected by endothermicity filtering
- The updated network and species database are publicly available

## Abstract

The gas-phase reaction networks are the backbone of astrochemical models. However, due to their complexity and non-linear impact on the astrochemical modeling, they can be the first source of error in the simulations if incorrect reactions are present. Over time, following the increasing number of species detected, astrochemists have added new reactions, based on laboratory experiments and quantum mechanics (QM) computations as well as reactions inferred by chemical intuition and similarity principle. However, sometimes no verification of their feasibility in the interstellar conditions, namely their exothermicity, was performed. In this work, we present a new gas-phase reaction network, GRETOBAPE, based on the KIDA2014 network and updated with several reactions, cleaned from endothermic reactions not explicitly recognized as such. To this end, we characterized all the species in the GRETOBAPE network with accurate QM calculations. We found that 5% of the reactions in the original network are endothermic although most of them are reported as barrierless. The reaction network of Si-bearing species is the most impacted by the endothermicity cleaning process. We also produced a cleaned reduced network, GRETOBAPE-red, to be used to simulate astrochemical situations where only C-, O-, N- and S- bearing species with less than 6 atoms are needed. Finally, the new GRETOBAPE network, its reduced version, as well as the database with all the molecular properties are made publicly available. The species properties database can be used in the future to test the feasibility of possibly new reactions.