  The formalism for exactly calculating the retarded and advanced Green's
functions of strongly correlated lattice models in a uniform electric field is
derived within dynamical mean-field theory. To illustrate the method, we solve
for the nonequilibrium density of states of the Hubbard model in both the
metallic and Mott insulating phases at half-filling (with an arbitrary strength
electric field) by employing the numerical renormalization group as the
impurity solver. This general approach can be applied to any strongly
correlated lattice model in the limit of large dimensions.
