Molecular Simulations for Astrophysics

The Joint Iberian Meeting on Atomic and Molecular Physics (IBER), Barcelona, September 12-14th, 2017. -- http://iber2017.com/index.phpIn order to interpret the abundances of the species detected in different astrophysical objects, it is necessary to provide accurate rates for the formation and destruction processes, typically reactive collisions and photodissociation. HCN and its isomer HNC are widely detected in space, and in photodissociation regions the HNC/HCN ratio presents anomalies. In order to understand their stability the photoabsorption cross section has been studied recently for the isomers in a wide range of excitation energies [1]. It is found that HNC has a significant larger absorption cross section than HCN, and it is therefore destroyed more efficiently by UV radiation. The reaction M+ + H2 ¿ MH+ + H are studied with quantum methods to obtain the state-to-state rates for simple hydrides like CH+ [2] and OH+[3], and their effect on the observed intensity of lines arising from excited rotational levels will be commented. H3+ plays a fundamental role in the formation of hydrides in colder environments. H3+ is created in H2+H2+ [4] collisions and its subsequent ortho/para transformation in the H2 +H3+ [5], which will also be described. In those cases a full quantum treatment is no possible at the low temperatures of interest, and the use of combined zero-point energy corrected quasi-classical results combined with statistical models to account for the nuclear spin permutation will be described. Finally, some recent improvements on the quantum description of H3++H2 exchange reactions will be described. [1] A. Chenel, O. Roncero, A. Aguado, M. Agúndez, and J. Cernicharo, J. Chem. Phys. 144, 144306 (2016); A. Aguado, O. Roncero, A. Zanchet, M. Agúndez, and J. Cernicharo, AstroPhys. J. 838:33 (2017) [2] A. Zanchet et al., Astrophys. J., 766:80 (2013). [3] S. Gómez-Carrasco et al., Astrophys. J., 794:33 (2014) [4] C. Sanz-Sanz, et al., J. Chem. Phys. 143, 234303 (2015) [5] S. Gómez-Carrasco, et al., J. Chem. Phys. 137, 094303 (2012)Peer Reviewe