To evaluate our methodology 1 in periodic systems, we look at a selection of metallic, ionic, semiconducting, and molecular crystals (Figure ). The BCC phase of K is an archetypical simple metal with good thermal and electric conductivity and high reactivity. The FCC phase of LiF is a wide band gap (ca. 14 eV) insulator composed of atoms on the opposite extremes of the electronegativity scale. GaN is probably the most heavily investigated of all the III-V nitride semiconductors. The wurtzite (P63mc) phase of GaN is a very hard material with a band gap of 3.4 eV. Finally, urea is a common molecular case study in crystallography. This material consist of high quality noncentrosymmetric tetragonal P-421m crystals with two molecules per unit cell and its charge density has been carfully studied using synchrotron X-ray and neutron diffraction . Urea is a good example when studying a range of interactions, including strong covalent bonds and weaker intermolecular hydrogen bonds. Our selection of materials is not meant to be exhaustive, but act as proof-of-concept for our methods' utility in distinguishing between different electronic structures in the condensed phase.