On the construction of the non-adiabatic nuclear kinetic energy operator for diatomic and triatomic systems

Abstract

The kinetic energy operator for triatomic molecules with coordinate dependent e ective nuclear masses has been derived in the framework of perturbation theory with respect to the ratio of the electron and proton mass. We have demonstrated that a ad-hoc introduction of the coordinate dependent nuclear masses in the Cartesian form of a trinuclear kinetic energy operator preserves the total rotational invariance of the problem. Obtained results can be used for analysis of the non-adiabatic e ects in the rotation- vibration spectra of triatomic molecules.