A graphical example of relativistic effects in molecules
The pictures shown here are electron densities resulting from a non-relativistic and a relativistic calculation on UF6. The spinor orbital shown is dominated by uranium 6s. The MO goes from strongly anti-bonding to almost non-bonding due to the contraction of the U 6s orbital. The density shown is represented with a logarithmic scale. Purple represents very low density and red is high density. Both pictures use the same colour scale.
These 3D pictures of electron densities were made by Jo Asplin from the university of Tromsø (Norway).