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.