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