On the non-adiabatic potentials in diatomic molecules

Abstract

The decomposition of non-adiabatic wavefunctions of diatomic molecules into electronic and vibrational functions is discussed and the properties of the resulting non-adiabatic pseudo-potentials are investigated. It is shown that the vibrational part of the wavefunction is nodeless and the corresponding pseudo-potential differs significantly from the adiabatic potential for all vibrationally excited (v ≠ 0) states. The differences take the form of potential barriers positioned at the nodes of the adiabatic vibrational function. It is argued that this excludes the possibility of defining an ab initio non-adiabatic potential that could have a practical significance.