  A density functional theory is used to predict the binding energy of atomic
and molecular impurities (Ne, Ar, Kr, Xe, Li, Na, K, Rb, Cs, and SF$_6$) in the
center of $^4$He clusters, in the limit of zero temperature and for zero
angular momentum states. The size dependence of the binding energy, from small
clusters to the bulk liquid limit, is investigated. The behaviour of the $^4$He
density near the impurity is also studied.
