  The surface tension, the adsorption, and the depletion thickness of polymers
close to a single nonadsorbing colloidal sphere are computed by means of Monte
Carlo simulations. We consider polymers under good-solvent conditions and in
the thermal crossover region between good-solvent and $\theta$ behavior. In the
dilute regime we consider a wide range of values of $q$, from $q = 0$ (planar
surface) up to $q\approx 30$-50, while in the semidilute regime, for
$\rho_p/\rho_p^*\le 4$ ($\rho_p$ is the polymer concentration and $\rho_p^*$ is
its value at overlap), we only consider $q = 0,0.5,1$ and 2. The results are
compared with the available theoretical predictions, verifying the existing
scaling arguments. Field-theoretical results, both in the dilute and in the
semidilute regime, are in good agreement with the numerical estimates for
polymers under good-solvent conditions.
