Further illustration of the different types of hybridizations is obtained from the projections of the charge densities around and between atoms. Figure presents the projections shown with yellow volumes. Upon crossing a crystal plane, charge density slices with red color are shown indicating strong charge localizations. In tet-C 4 (Fig. ) the sp 3 -type hybridization is best described at central carbon with the yellow volumes taking the shape of a tetrahedron.