Effects of the potential on surface states

Surface states are calculated for high-symmetry points in the Brillouin zone of a (001) aluminum film using a pure overlap potential and a Cambridge potential. Results are compared with those of previous calculations to see how surface states are affected by the differences in potential. This comparison shows that behavior of the potential over the last few occupied layers is more important than the way the potential goes to zero outside the jellium edge. some suggestions are made about the range of validity of the Cambridge model of the potential.