  In this paper, we calculate the stress-energy tensor for a quantized massless
conformally coupled scalar field in the background of a conformally flat
brane-world geometries, where the scalar field satisfying Robin boundary
conditions on two parallel plates. In the general case of Robin boundary
conditions formula are derived for the vacuum expectation values of the
energy-momentum tensor. Further the surface energy per unit area are obtained .
As an application of the general formula we have considered the important
special case of the AdS$_{4+1}$ bulk, moreover application to the
Randall-Sundrum scenario is discused. In this specific example for a certain
choice of Robin coefficients, one could make the effective cosmological
constant vanish.
