THE QUANTUM MECHANICAL CALCULATION OF THE SURFACE ENERGY OF SODIUM CHLORIDE— A FIRST APPROXIMATION

Löwdin's theory for the cohesive energy of alkali halides has been used to calculate a first approximation to the surface energy of a {100} face of sodium chloride. The value found, 187 ergs/cm.2, differs from the experimental value determined by measuring heats of solution (276 ergs/cm.2) but is about 18% higher than the figure obtained from a corresponding classical model. For comparison the surface energies of several other alkali halides have been computed.