  We report on first-principle based studies of the adsorption interaction of
astatine species on a gold surface. These studies are aimed primarily at the
support and interpretation of gas chromatographic experiments with Superheavy
Elements, tennessine (Ts, $Z=117$) as the heavier homologue of At and possibly
nihonium (Nh, $Z=113$) as its pseudo-homologue. The adsorption energies of
elemental astatine or the corresponding monohydroxide on a stable gold (111)
surface are estimated using gold clusters with up to 69 atoms in order to
simulate the adsorption site. To simulate the electronic structure of $\rm
At-Au_n$ and $\rm AtOH-Au_n$ complexes, we combine accurate shape-consistent
relativistic pseudopotentials and non-collinear two-component relativistic
density functional theory. The predicted adsorption energies for At and AtOH on
gold are $\rm 130 \pm 10$ kJ/mol and $\rm 90 \pm 10$ kJ/mol, respectively.
