Hannover 2013 – scientific programme
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MO: Fachverband Molekülphysik
MO 13: Quantum Chemistry and Molecular Dynamics II
MO 13.6: Talk
Tuesday, March 19, 2013, 15:15–15:30, F 107
Beyond the Born-Oppenheimer approximation in the spectroscopy of three-body systems — •René Jestädt1, Heiko Appel1, Alison Crawford Uranga2, Lorenzo Stella2, and Angel Rubio1,2 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany — 2Nano-Bio Spectroscopy group, Departamento Física de Materiales, Universidad del País Vasco, Centro de Física de Materiales CSIC-UPV/EHU-MPC and DIPC, San Sebastiàn, Spain
In this work we utilize a Lagrange-Laguerre variational method [1] to construct highly accurate numerical solutions for non-relativistic three-body systems (Helium atom, H2+, HD+ and dtµ in 3D). Our approach does not rely on the Born-Oppenheimer approximation. This allows us to investigate the mass-dependence of optical dipole absorption spectra. For the molecular systems H2+, HD+ and dtµ, we find pronounced mass dependence of the dipole transition matrix elements and the appearance of a new excitation close to the second ionization threshold that is not in a Born-Oppenheimer description of the molecular system. We compare our 3D results to one-dimensional model calculations and provide a mechanism in terms of non-adiabatic coupling elements.