  We present a first-principles calculation of the electronic properties of
crystalline silicon and gallium arsenide in a uniform electric field. Polarized
Wannier-like functions which are confined in a finite region are obtained by
minimizing a total-energy functional which depends explicitly on the
macroscopic polarization of the solid. The polarization charge density and the
electronic dielectric constant are computed via finite differences. The results
coincide with those of the linear response approach in the limit of vanishing
electric field and infinite localization region.
