TheTmatrix, theKmatrix, d bands andl-dependent pseudo-potentials in the theory of metals

The `Green's function' method for the calculation of electronic band structure is investigated. The general T-matrix theory of Beeby and Edwards is used to transform the formulae of Korringa and of Kohn and Rostoker to a `reciprocal lattice representation' which is equivalent to a `nearly free electron' formalism. The matrix elements between plane waves then correspond to a `pseudo-potential', which depends mainly on the phase shifts of the atomic potentials but which is also a function of the wave vector and energy of the Bloch state being considered. For small phase shifts it tends to the scattering amplitude or `quasi-potential' of an atomic potential.