Cone states of tri-hydrogen isotopomers and criterion for the geometric phase effect

We report calculations of the vibrational spectrum of μH2/HD/DT as well as D3 in their first-excited electronic state, both with the inclusion of the geometric phase effect and without including it. The results show that, especially for μHD and μDT, it plays a minor role for the first 30 vibrational levels of such systems. This can be rationalized from the tilting of the C3-axis due to mass effects. A simple phenomenological criterion for the relative role of the GP effect in tri-hydrogen isotopomers has been suggested.