HCl, DCl and TCl diatomic molecules in their ground state: predicting Born–Oppenheimer rovibrational spectra

Abstract

The analytic Born–Oppenheimer (B-O) potential curve for the ground state of the molecule (H,D,T)Cl is constructed for the whole range of internuclear distances with an accuracy of 3–5 significant figures in comparison with the Rydberg–Klein–Rees-style potential curve derived from available experimental data on vibrational energies. With an accuracy of 3–4 significant figures, energy predictions are made for HCl (DCl, TCl) for the 836 (1625, 2366) B-O rovibrational bound states with maximal vibrational number and maximal angular momentum , including 24 (46, 63) weakly-bound states (close to the dissociation limit) with energies Hartree. The insufficiency of existing experimental data is indicated, and predictions for the bulk of the missing rovibrational states are made for all HCl, DCl, and TCl molecules.