  In this work we examine the electrostatic screening potential due to a point
charge located off-centre in a spherical dielectric cavity. This potential is
expanded for the case in which the dielectric constant $\epsilon$ is large,
several methods of finding the terms in the expansion are investigated, and
closed-form expressions are found through third order in $\epsilon$ along with
error bounds. Finally, possible uses of these expressions in molecular dynamics
simulations of isolated charged molecules is discussed.
