Ab initio spectroscopy of Van der Waals molecules: a comparison of three different theoretical methods applied to NeHF and NeDF

Three ab initio methods, namely MP2, CCSD(T) and SIMPER-1K, are used to calculate the intermolecular potential between neon and a rigid HF molecule. The energies of Van der Waals rovibrational bound states are calculated from the potential energy surfaces, and compared with previously published high-resolution spectra. The MP2 method does not predict all the observed bound states, but the SIMPER-1K and CCSD(T) methods both give good agreement with the experimental results. Using the SIMPER-1K method, rotational constants differ from experiment by less than 10%, stretching and bending frequencies by less than 3% and centrifugal distortion constants by less than 4%.