  Fermionic atoms in a periodic optical lattice provide a realization of the
single-band Hubbard model. Using Quantum Monte Carlo simulations along with the
Maximum Entropy Method, we evaluate the effect of a time-dependent perturbative
modulation of the optical lattice amplitude on atomic correlations, revealed in
the fraction of doubly-occupied sites. Our treatment extends previous
approaches which neglected the time dependence of the on-site interaction, and
shows that this term changes the results in a quantitatively significant way.
The effect of modulation depends strongly on the filling-- the response of the
double occupation is significantly different in the half-filled Mott insulator
from the doped Fermi liquid region.
