Bands and Bonds

The chemical bond arises from a redistribution of electronic charge when atoms are brought in close proximity. The bond in a solid results from the superposition of charge densities of all atoms in the system. In an atom all electrons reside in their ground states at equilibrium. Only a few low lying excited states are typically accessed. The chemical bond in the solid consists of excited electronic configurations which are created to satisfy the constraints of a minimum energy, semi-infinite solid. These constraints create not only a variation on atomic energy level structure, but a compromise between the limiting classifications of bonding. These limiting classifications and their compromises are discussed in this section.