  The phononless hopping conductivity of a disordered system with localized
states is studied in a broad range of frequencies by straightforward computer
simulations taking into account Coulomb interactions. At sufficiently low
temperatures, the conductivity is determined by the zero-phonon absorption of
the photon by pairs of states. The laser frequency dependence of the
conductivity is examined and compared with the analytical model of Efros and
Shklovskii and with recent experimental data obtained on Si:P. The range of
parameters is determined, for which the conductivity dependence on photon
energy best reproduces the experimental results.
