Heavier than Xe

[ChrisW]

Anyone know how I might be able to use CE on complexes post Xe. The website suggests

"If you want to generate surfaces or map surface properties which require a wavefunction on structures containing trans-Xe elements the Clementi-Roetti basis-set is insufficient and you must use the Thakkar basis-set. You can choose the Thakkar in Preferences→Expert Settings→Internal Basis-set."

but I don't seems to be able to do this in the version that I have.

Any other suggestions, other than just changing the metal to a lighter element (I can do this), would be appreciated!

Cheers
Chris