Fermi liquid, periodic

Note that the exchange term is of the form / y(r,r ) h(r )dr instead of the y (r) (r) type. Equation (1.12), known as the Hartree-Fock equation, is intractable except for the free-electron gas case. Hence the interest in sticking to the conceptually simple free-electron case as the basis for solving the more realistic case of electrons in periodic potentials. The question is how far can this approximation be driven. Landau s approach, known as the Fermi liquid theory, establishes that the electron-electron interactions do not appear to invalidate the one-electron picture, even when such interactions are strong, provided that the levels involved are located within kBT of Ep. For metals, electrons are distributed close to Ep according to the Fermi function f E) ... 

A different approach was used by Razafimandimby et al. (1984), d Am-brumenil and Fidde (1985) and Fulde et al. (1988) for the Kondo lattice to calculate quasiparticle bands. They start from the observation, Nozieres (1974), that for r a Fermi liquid description can be used for the scattering by Kondo ions. Its phase shift is assumed to have a resonant behaviour around the Fermi energy, with T defining the energy scale. A periodic lattice of resonant scattering centers then leads to narrow quasipartiele bands, whieh have been caleulated within the KKR formalism. In the simplest approximation they are equivalent to those obtained from the mean-field approximation of the Anderson lattice. The method of Razafimandimby et al. has been used for a realistic... 

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