Abstract book - Prof. Per Jensen, Ph.D. - Bergische Universität ...

Poster session, H34 147High Level Ab Initio Study of the Electronic Interactions betweenEight Lowest Electronic States of the C 2 RadicalSergei N. Yurchenko, 1 Jonathan Tennyson, 1 István Szabó, 2 Timothy W. Schmidt, 3George B. Bacskay, 3 and Andrey V. Stolyarov 41 Department of Physics and Astronomy, University College London, London, WC1E6BT, UK2 Laboratory of Molecular Structure and Dynamics, Institute of Chemistry, EötvösUniversity, H-1518 Budapest 112, P.O. Box 32, Hungary3 School of Chemistry, University of Sydney, New South Wales 2006, Australia4 Department of Chemistry, Moscow State University, GSP-2 Leninskie gory 1/3,Moscow 119992, RussiaYurchenko S.N.Tennyson J.Szabo I.Schmidt T.W.Bacskay G.B.Stolyarov A.V.C 2 plays an important role in the chemistry of the cool stars. It has been observed inmany extraterrestrial sources, such as comets, carbon stars, protoplanetary nebulae andmolecular clouds. We present an accurate and detailed ab initio study of the couplingbetween the electronic states X 1 , A 1 u , B 1 g , B’ 1 a 3 u b 3 c 3 and d 3 g ofthe C 2 molecule. Potential energy and transition moment curves for these states wererecently 1 computed ab initio using the MRCI method in conjunction with the aug-ccpV6Zbasis set including the core and core-valence correlations and scalar relativisticenergy corrections as implemented in the MOLPRO.Presently we apply the same level of theory to obtain all spin-orbit interaction as well ascoupling functions associated with the electronic angular momentum on a large gridof geometries. The corresponding electronically averaged functions are computed atthe CASSCF level.We have determined all spin-vibronic energy levels of 12 C 2 associated with these eightstates up to 20000 cm -1 above the electronic ground-state minimum using the rovibronicprogram Duo developed recently for a general diatomic molecule of an arbitrary numberof electronic states. The comparison with and an empirical tuning to the experimentaldata available in the literature will be presented and discussed.C 2 is one of the species selected for the ExoMol project (see www.exomol.com), whichaims to generate accurate and comprehensive line lists for molecules of keyastronomical importance.This work is supported by ERC Advanced Investigator Project 267219.References[1] T. W. Schmidt and G. B. Bacskay, J. Chem. Phys. 127, 234310 (2007)