First principles studies of a Xe atom adsorbed on Nb(110) surface
  We study adsorption sites of a single Xe adatom on Nb(110) surface using a density functional theory approach: The on-top site is the most favorable position for the adsorption. We compare the binding features of the present study to earlier studies of a Xe adatom on close-packed (111) surface of face-centered cubic metals. The different features are attributed through a microscopic picture to the less than half filled d-states in Nb. 
S. Dag, M. Shaughnessy, C. Y. Fong, X. D. Zhu, L. H. Yang
cond-mat.mtrl-sci cond-mat.mes-hall cond-mat.other