  Bounded plasmas are characterized by a rapid but smooth transition from
quasi-neutrality in the volume to electron depletion close to the electrodes
and chamber walls. The thin non-neutral region, the boundary sheath, comprises
only a small fraction of the discharge domain but controls much of its
macroscopic behavior. Insights into the properties of the sheath and its
relation to the plasma are of high practical and theoretical interest. The
recently proposed smooth step model provides a closed analytical expression for
the electric field in a planar, radio-frequency modulated sheath. It represents
(i) the space charge field in the depletion zone, (ii) the generalized Ohmic
and ambipolar field in the quasi-neutral zone, and (iii) a smooth interpolation
for the transition in between. This investigation compares the smooth step
model with the predictions of a more fundamental particle-in-cell/Monte Carlo
collisions simulation and finds good quantitative agreement when the assumed
length and time scale requirements are met. A second simulation case
illustrates that the model remains applicable even when the assumptions are
only marginally fulfilled
