  We present a clear and rigorous derivation of the Ewald-like method for
calculation of the electrostatic energy of the systems infinitely periodic in
two-dimensions and of finite size in the third dimension (slabs) which is
significantly faster than existing methods. Molecular dynamics simulations
using the transferable/polarizable model by Rustad et al. were applied to study
the surface relaxation of the nonhydroxylated, hydroxylated, and solvated
surfaces of alpha-Fe2O3 (hematite). We find that our nonhydroxylated structures
and energies are in good agreement with previous LDA calculations on
alpha-alumina by Manassidis et al. [Surf. Sci. Lett. 285, L517, 1993]. Using
the results of molecular dynamics simulations of solvated interfaces, we define
end-member hydroxylated-hydrated states for the surfaces which are used in
energy minimization calculations. We find that hydration has a small effect on
the surface structure, but that hydroxylation has a significant effect. Our
calculations, both for gas-phase and solution-phase adsorption, predict a
greater amount of hydroxylation for the (012) surface than for the (001)
surface. Our simulations also indicate the presence of four-fold coordinated
iron ions on the (001) surface.
