An accurate isotopically invariant potential function of the hydrogen sulphide molecule

The potential function of the electronic ground state of the hydrogen sulphide molecule is obtained by the simultaneous fit of a very large sample of high-resolution vibration–rotation data. The use of an extensive set of more than 12 000 experimental rovibrational transitions, corresponding to 4175 rovibrational states with Jmax=15, Ka max=15 for bands of 7 isotopomers (H232S,H233S,H234S,D232S,D234S, HD32S, and HD34S), allows improved calculations of `local-mode statesʹ and highly excited bending-rotational states. The root-mean-square (RMS) deviation of the rovibrational fit is 0.05 cm−1. For the entire set of all 73 band centres of all isotopic species for which experimental data exists, the RMS deviation of the results of calculations with a single isotopic invariant potential function is 0.03 cm−1.