  The paper introduces a semi-analytical method for calculating the Hall
conductivity in the single-band approximations. The method goes beyond the
linear response theory and, thus, imposes no limitation on the electric fields
magnitude. It is shown that the Hall current decreases with increase of the
electric field, if the Bloch frequency (which is proportional to the electric
field) exceeds the cyclotron frequency (which is proportional to the magnetic
field). The obtained results can be directly applied to the system of cold Bose
atoms in a 2D optical lattice, where the single-band approximation is well
justified.
