  We develop a method for the calculation of ballistic transport from first
principles. The multiple scattering screened Korringa-Kohn-Rostoker (KKR)
method is combined with a Green's function formulation of the Landauer approach
for the ballistic transport. We obtain an efficient O(N) algorithm for the
calculation of ballistic conductance through a scattering region connected to
semi-infinite crystalline leads. In particular we generalize the results of
Baranger and Stone in the case of Bloch wave boundary conditions and we discuss
relevant properties of the S-matrix. We consider the implications on the
application of the formalism in conjunction with a cellular multiple scattering
description of the electronic structure, and demonstrate the convergence
properties concerning the angular momentum expansions.
