  The aim of this article is to propose a mathematical model describing the
electronic structure of crystals with local defects in the framework of the
Thomas-Fermi-von Weizs\"acker (TFW) theory. The approach follows the same lines
as that used in {\it E. Canc\`es, A. Deleurence and M. Lewin, Commun. Math.
Phys., 281 (2008), pp. 129--177} for the reduced Hartree-Fock model, and is
based on thermodynamic limit arguments. We prove in particular that it is not
possible to model charged defects within the TFW theory of crystals. We finally
derive some additional properties of the TFW ground state electronic density of
a crystal with a local defect, in the special case when the host crystal is
modelled by a homogeneous medium.
