  We study the response of single nanosized spherical colloids in electrolyte
solution to an alternating electric field (AC field) by computer simulations.
We use a coarse-grained mesoscopic simulation approach that accounts in full
for hydrodynamic and electrostatic interactions as well as for thermal
fluctuations. The solvent is modeled as a fluid of single Dissipative Particle
Dynamics (DPD) beads, and the colloidal particle is modeled as a rigid body
made of DPD beads. We compute the mobility and the polarizability of a single
colloid and investigate systematically the effect of amplitude and frequency of
the AC-fields. Even though the thickness of the Debye layer is not "thin"
compared to the radius of the colloid, and the thermal fluctuations are
significant, the results are in good agreement with the theoretical prediction
of the Maxwell-Wagner-O'Konski theory, especially for uncharged colloids.
