Interaction potentials and spectroscopy of Hg+.Rg and Cd+.Rg and transport coefficients for Hg+ and Cd+ in Rg (Rg=He-Rn).

High-level ab initio calculations have been performed on the Hg(+).Rg and Cd(+).Rg species, where Rg-He-Rn. Potential-energy curves have been calculated over a wide range of internuclear separation, sampling the repulsive, equilibrium, and long-range regions. From these curves, rovibrational and spectroscopic constants were derived and compared to those available from previous studies. In addition, transport coefficients were calculated and compared to the available experimental data for the cases of Hg(+) in He, Ne, and Ar. There are two interesting features relating to the mobility results. One is the development of a "mobility minimum" for Hg(+) in the heavier rare gases--with weaker minima being found for Cd(+); a "rule of thumb" is presented for determining when mobility minima might appear. The second is that excellent agreement is found for the direct calculation of mobilities for Hg(+) in (22)Ne, and those obtained by scaling the (20)Ne mobilities. The latter result allows us to conclude that the mobilities of the various combinations of isotopes can be calculated from the results herein via a mass scaling.