Approximated treatment of electrons in a periodic potential: tight-binding approach (Nov. 24)

The tight-binding approach: introduction, general formulation; the simplified case of s-band arising from a single atomic s-level. Tight-binding in crystals with inversion symmetry; band dispersion. (A&M, ch. 10).

Exercise: tight-binding: s-band arising from a 1D linear chain of atoms, density of states; half filling of band.

s-band in 2D square lattice: band dispersion along some high symmetry directions, energy isosurfaces in the Brillouin zone.