  We present and analyze a model for the combination of bulk and surface
electroclinic effects in the smectic-A* (Sm-A) phase near a Sm-A*--Sm-C*
transition. As part of our analysis we calculate the dependence of the surface
tilt on external electric field and show that it can be eliminated, or even
reversed from its zero-field value. This is in good agreement with previous
experimental work on a system (W415) with a continuous Sm-A*--Sm-C* transition.
We also analyze, for the first time, the combination of bulk and surface
electroclinic effects in systems with a first order Sm-A*--Sm-C* transition.
The variation of surface tilt with electric field in this case is much more
dramatic, with discontinuities and hysteresis. Near each type of Sm-A*--Sm-C*
transition we obtain the temperature dependence of the field required to
eliminate surface tilt. Additionally, we analyze the effect of varying the
system's enantiomeric excess, showing that it strongly affects the field
dependence of surface tilt, in particular, near a first order Sm-A*--Sm-C*
transition. In this case, increasing enantiomeric excess can change the field
dependence of surface tilt from continuous to discontinuous. Our model also
allows us to calculate the variation of layer spacing in going from surface to
bulk, which in turn allows us to estimate the strain resulting from the
difference between the surface and bulk layer spacing. We show that for certain
ranges of applied electric field, this strain can result in layer buckling
which reduces the overall quality of the liquid crystal cell. For de Vries
materials, with small tilt-induced change in layer spacing, the induced strain
for a given surface tilt should be smaller. However, we argue that this may be
offset by the fact that de Vries materials, which typically have Sm-A*--Sm-C*
transitions near a tricritical point, will generally have larger surface tilt.
