  A many-body expansion for the computation of the charge form factor in the
center-of-mass system is proposed. For convergence testing purposes, we apply
our formalism to the case of the harmonic oscillator shell model, where an
exact solution exists. We also work out the details of the calculation
involving realistic nuclear wave functions. Results obtained for the Argonne
$v$18 two-nucleon and Urbana-IX three-nucleon interactions are reported. No
corrections due to the meson-exchange charge density are taken into account.
