title: Perturbations in vibrational diatomic spectra: factorization of the molecular wave function.
abstract: The coupling between two electronic states of a diatomic molecule may lead to an erratic behaviour of the associated vibrational energies. An example is the homogeneous coupling between the valence b' state and the Rydberg c' state of the N2 molecule, both of symmetry (1)Σu (+). The standard treatment of such a situation is to write the wave function as a sum of two Born-Oppenheimer products. It has recently been argued [L. S. Cederbaum, J. Chem. Phys. 138, 224110 (2013); N. I. Gidopoulos and E. K. U. Gross, Philos. Trans. R. Soc., A 372, 20130059 (2014)] that even in such a case the wave function should be representable as a single product, with an electronic factor depending parametrically on nuclear positions and a nuclear factor. We setup such a representation in the case of the perturbations in the N2 molecule.
authors.affiliation: Institut des Sciences Moléculaires d' Orsay (ISMO), Bât. 350, Univ. Paris-Sud (CNRS), 91405 Orsay, France and U.F.R. de Physique Fondamentale et Appliquée, Université Pierre et Marie Curie, 75321 Paris, France.
authors.forename: R
authors.initials: R
authors.lastname: Lefebvre