Multiconfiguration Hartree-Fock Method

This chapter discusses the multiconfiguration HartreeFock (MCHF) method, in which the wave function is approximated by a function that is a linear combination of configuration state functions. When the MCHF method is used it is convenient to partition the configuration states in such a way that the first-order set contains all configuration states interacting with one or more of the zero-order configuration states. Topics considered include the Hartree-Fock approximation, Brillouin's theorem, the LS dependence, correlation and the MCHF approximation (zero- and first-order sets, Brillouin's theorem and interaction with series, unconstrained orbitals, reduced forms), excited states, transition metals, relativistic corrections, and transition probabilities (a first-order theory for oscillator strengths, core polarization and ionization energies, f value trends, relativistic effects)