Course

Quantum theory of phonons; Debye Model; electron-phoning interactions.

Stoner model for ferromagnetism (Hubbard model); magnetic polarization; accoustic and optical phonons.

Effective action to one loop

Hartree and Hartree-Fock equations; Self-energy; Screening (Yukawa potential); Stoner model for ferromagnetism (Hubbard model).

Structure of perturbation theory, Generating functionals

Peierl's theorem; Fermi surface; relative importance of average KE vs. average PE; density of states; Mean Field Theory.

Perturbation theory for φ4 theory, Feynman diagrams

Tight binding model; Nearly free electrons (unperterbed solution, zone folding, brief discussion of unperturbed solution).

Wick's theorem, UV and IR divergences in the free scalar propagator, Operator product expansion