  In this paper we present an approach aimed at performing many-body
calculations of Born-effective charges of crystalline insulators, by including
the electron-correlation effects. The scheme is implemented entirely in the
real space, using Wannier-functions as single-particle orbitals. Correlation
effects are computed by including virtual excitations from the Hartree-Fock
mean field, and the excitations are organized as per a Bethe-Goldstone-like
many-body hierarchy. The results of our calculations suggest that the approach
presented here is promising.
