Application to Crystals

Abstract

Considering the crystal as a giant molecule, one could suppose that after having performed an self-consistent field (SCF) treatment, which yields delocalized molecular orbitals belonging to the group of lattice symmetry and therefore possessing translational network symmetry, one can then localize these orbitals by suitable unitary transformation. As with the molecules of finite size, one would obtain: (1) localized orbitals around diverse nuclei, identifying themselves with the inner atomic orbitals of isolated atoms, (2) localized orbitals around one or more nuclei, corresponding to lone pairs or to bonds, in the classical sense, and (3) eventually also molecular orbitals that are not localizable.