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

Poster session, H16 129ExoMol Molecular Line Lists for Astrophysical Applications:A Theoretical Line List for Aluminum OxideAndrei Patrascu, Sergei N. Yurchenko, Jonathan TennysonUniversity College London, Dept of Physics and Astronomy, Gower Street, LondonWC1E 6BT, UKPatrascu A.Yurchenko S.N.Tennyson J.ExoMol (www.exomol.com) is an ERC project aiming to systematically provide linelists which can be used for spectral characterisation and simulation of astrophysicalenvironments such as exoplanets, brown dwarfs, cool stars and sunspots 1 . The listExoMol molecules include diatomics (e.g., C 2 , O 2 , AlO, NiH, MgH, CrH), triatomics(e.g., H 2 S, C 3 , SO 2 ), tetratomics (e.g., PH 3 , HOOH, H 2 CO) and a few larger molecules(most notably CH 4 and HNO 3 ) which currently lack a comprehensive spectroscopicdescription.We report progress on a new theoretical line list for Aluminium Oxide. The ro-vibronicenergy levels of AlO are determined by solving variationally a Schrödinger equation fora system of coupled electronic states X 2 Σ + , B 2 Σ + and A 2 Π using an in-house FORTRANcode; the couplings between the curves are due to interactions between electronic orbitaland electronic spin angular momenta. The ab initio potential energy and couplingcurves were obtained using the Multi-Configuration-Self-Consistent-Field (MCSCF)and Internally-Contracted Multi-Reference-Configuration-Interaction with Davidsoncorrection (IC-MRCI+Q) methods in conjunction with the basis sets of the (up to) the6-ζ quality. The effects of the basis set truncation error, choice of the complete activespace, core-correlation and relativistic corrections as well as sensitivity of angularmomentum coupling curves with respect to the electron correlation level used werecarefully analysed. The quality of the ab initio methods used for the electronic structurecalculations can be assessed by comparing the theoretical ro-vibronic energies to theexperimental data available in the literature, which are also used to semi-empiricallyrefine the potential energy curves and different couplings.This work is supported by ERC Advanced Investigator Project 267219.References[1] J. Tennyson and S. N. Yurchenko, MNRAS (2012), in press; arXiv:1204.0124