SOME CALCULATIONS OF THE SURFACE ENERGY OF MAGNESIUM OXIDE

Calculations of the surface energy of an undistorted {100} face of crystalline magnesium oxide have been made. An exponential form of the repulsive energy term was used, and the van der Waals attractive energy between dipoles was included, as in the Born–Mayer treatment of cohesive energy. Comparison with earlier work is made, and it is shown that results are markedly dependent upon the form of the repulsive potential term, the inclusion of the van der Waals term, and, indeed, the choice of coefficients of the van der Waals term. This is not the case so far as the calculated cohesive energies are concerned. The results indicate that a Born–Mayer model may be inadequate in the case of magnesium oxide, and that caution must be exercised before accepting surface energies arrived at by such calculations.