About: Hill limit (solid-state)

In solid-state physics, the Hill limit is a critical distance defined in a lattice of actinide or rare-earth atoms. These atoms own partially filled or levels in their valence shell and are therefore responsible for the main interaction between each atom and its environment. In this context, the hill limit is defined as twice the radius of the -orbital. Therefore, if two atoms of the lattice are separate by a distance greater than the Hill limit, the overlap of their -orbital becomes negligible. A direct consequence is the absence of hopping for the f electrons, ie their localization on the ion sites of the lattice.