Calculated properties of XeH2

Relativistic pseudopotential calculations (including spin-orbit (SO) effects) are reported for XeH2 at levels up to MRCISD and CCSD(T). Three relativistic and one non-relativistic pseudopotential are tested. The 18-valence-electron (Xe) CCSD(T) results, including BSSE and SO, give Re and De of 191.6 pin and 0.32 eV, respectively. Adding estimates of 0.03 eV for a MRCI dissociation threshold and 0.03 eV for matrix quadrupole stabilisation, the ground-state well depth obtained is comparable with the sum of the zero-point vibrations and one observed vibration. The calculated σg and πu frequencies are comparable with the observed ones. Test results for XeH+ are reported.