Accurate intermolecular ground state potential of the He-HCl van der Waals complex

We evaluate the rovibrational spectrum of the He-HCl van der Waals complex from an accurate ground state intermolecular potential, obtained from CCSD(T) interaction energies. After a systematic basis set study, we select the aug-cc-pV5Z basis set extended with midbond functions. The potential is characterized by two linear minima, i.e., He-ClH and He-HCl, with distances from the He atom to the HCl centre of mass of 3.349 and 3.832 Å, respectively; and energies of −32.74 and −31.16 cm−1, respectively. The rovibrational spectra for the different isotopic species are calculated. The results are compared to those previously available.