When Ashcroft returned to the ground state of metallic hydrogen in 1984, he assumed that the protons occupied the sites of a rigid Bravais lattice .
The work supported Wigner and Huntington's  contention that a layered Bravais lattice form of metallic hydrogen was the most stable in the 380[+ or -]50 to 860[+ or -] 100 GPa range .
Table 4 shows that most organic compounds crystallize in a triclinic, monoclinic, or orthorhombic Bravais lattice with the primitive lattice (87.
Furthermore, Lattices II-IV are all derivative sublattices of a cubic I-centered Bravais lattice and are all characterized by specialized reduced forms.
Two model examples--hexamethylbenzene, a centrosymmetric crystal with both covalent and Van der Waals bonds, and anhydrous alum, a nocentrosymmetric structure typical of ceramics and metals--are chosen as model crystals and used to explain symmetry, point groups, space groups, Bravais lattices
, reciprocal lattices, and diffraction maxima.