Graduate Quantum

The Wolff single-cluster algorithm for the 2D Ising model, and the statistics trouble near the critical point.

Exponential operators, Gram-Schmidt on degenerate eigenfunctions, the classical limit of the commutator, and density matrices for polarized light.

Local functionals place charge-transfer states several electron volts too low, and the failure traces to a single missing exchange term in the response equations.

The simplest post Hartree-Fock route to excited states, and the properties that keep it in use.