Effect of Phase Choices in Rovibrational Wavefunctions on the Labeling of K- and /-Type Doubling in Molecular Energy Levels

The change in phase factor of the wavefunction does not affect the absolute value of the matrix element, but does change the phase factor of the off-diagonal matrix element. This phase dependence causes a serious confusion in the sign of some parameters in the molecular Hamiltonian, which appear only in the off-diagonal matrix element; for example, the sign of the /-type doubling constant q of a linear or a symmetric-top molecule. In the present paper, the energy eigenvalues, symmetry species, and labeling of the eigenfunctions are discussed for the K-type doubling of asymmetric-top molecules and for the /-type doubling of linear or symmetric-top molecules in relation to the choices of phases in the basis wavefunctions.