The effects of exchange and correlation on the computed equilibrium shapes of wet MgO crystallites

The surface energies of clean and hydrated low-index surfaces of MgO are computed either within the LDA or the GGA. Their ratio is almost constant for the clean surfaces. However, when the temperature and pressure dependent water adsorption contribution to the surface energy is added, the relative stability of distinct wet or hydrated faces is sensitively affected by the actual choice of the functional, especially in the temperature range where water desorption occurs. The consequences on the Wulff’s shapes of MgO crystallites are discussed.