We present an alternative method for the exact calculations of the Wannier-
Stark (WS) localization in a long periodic potential corresponding to a (50
Angstrom /30 Angstrom) GaAs/Ga0.7Al0.3As superlattice. We show that the el
ectric held dependence of the electron wavefunction has unique localization
dynamics. One interesting prediction is a small effect involving the chang
e of the dipole field with increasing WS field. It is argued that this may
give rise to parasitic effects in Bloch oscillations and, therefore, to noi
se in coherent terahertz emission. (C) 2001 Academic Press.