  We propose a new, alternative method for ab-initio calculations of the
electronic structure of solids, which has been specifically adapted to treat
many-body effects in a more rigorous way than many existing ab-initio methods.
We start from a standard band-structure calculation for an effective
one-particle Hamiltonian approximately describing the material of interest.
This yields a suitable set of one-particle basis functions, from which well
localized Wannier functions can be constructed using a method proposed by
Marzari and Vanderbilt. Within this (minimal) basis of localized Wannier
functions the matrix elements of the non-interacting (one-particle) Hamiltonian
as well as the Coulomb matrix elements can be calculated. The result is a
many-body Hamiltonian in second quantization with parameters determined from
first principles calculations for the material of interest. The Hamiltonian is
in the form of a multi-band Hamiltonian in second quantization (a kind of
extended, multi-band Hubbard model) such that all the standard many-body
methods can be applied. We explicitly show how this approach can be solved in
the simplest many-body approximation, the mean-field Hartree-Fock approximation
(HFA), which takes into account exact exchange and corrects for
self-interaction effects.
