title: Core-mass nonadiabatic corrections to molecules: H2, H2+, and isotopologues.
abstract: For high-precision calculations of rovibrational states of light molecules, it is essential to include non-adiabatic corrections. In the absence of crossings of potential energy surfaces, they can be incorporated in a single surface picture through coordinate-dependent vibrational and rotational reduced masses. We present a compact method for their evaluation and relate in particular the vibrational mass to a well defined nuclear core mass derived from a Mulliken analysis of the electronic density. For the rotational mass we propose a simple, but very effective parametrization. The use of these masses in the nuclear Schrödinger equation yields numerical data for the corrections of a much higher quality than can be obtained with optimized constant masses, typically better than 0.1 cm(-1). We demonstrate the method for H(2), H(2)(+), and singly deuterated isotopologues. Isotopic asymmetry does not present any particular difficulty. Generalization to polyatomic molecules is straightforward.
authors.affiliation: Laboratório de Átomos e Moléculas Especiais, Departamento de Física, ICEx, Universidade Federal de Minas Gerais, P. O. Box 702, 30123-970 Belo Horizonte, MG, Brazil. leogabriel@timoteo.cefetmg.br
authors.forename: Leonardo G
authors.initials: LG
authors.lastname: Diniz
authors.forename: Alexander
authors.initials: A
authors.lastname: Alijah
authors.forename: José Rachid
authors.initials: JR
authors.lastname: Mohallem