title: Darwin and mass-velocity relativistic corrections in non-Born-Oppenheimer variational calculations.
abstract: The Pauli approach to account for the mass-velocity and Darwin relativistic corrections has been applied to the formalism for quantum mechanical molecular calculations that does not assume the Born-Oppenheimer (BO) approximation regarding separability of the electronic and nuclear motions in molecular systems. The corrections are determined using the first order perturbation theory and are derived for the non-BO wave function of a diatomic system expressed in terms of explicitly correlated Gaussian functions with premultipliers in the form of even powers of the internuclear distance. As a numerical example we used calculations of the transition energies for pure vibrational states of the HD(+) ion.
authors.affiliation: Department of Chemistry, Nicholas Copernicus University, ul. Gagarina 7, PL 87-100 Toruń, Poland.
authors.forename: Dariusz
authors.initials: D
authors.lastname: Kedziera
authors.forename: Monika
authors.initials: M
authors.lastname: Stanke
authors.forename: Sergiy
authors.initials: S
authors.lastname: Bubin
authors.forename: Maria
authors.initials: M
authors.lastname: Barysz
authors.forename: Ludwik
authors.initials: L
authors.lastname: Adamowicz