STRESS CALCULATIONS ON DIAMOND SURFACES

Calculations were carried out to evaluate stresses for atoms located i n the top several layers of the (100)-(1 x 1), (100)-(2 x 1) and (111) -(1 x 1) surfaces of diamond. Only equilibrated surfaces were taken in to consideration in this investigation. Stress values in the direction perpendicular to the exposed surface vanish. In lateral directions, h owever, stresses have non-vanishing values, in general. For the (100) surfaces calculated stress values are anisotropic. While the (2 x 1) r econstructed surface is under compression in both directions, calculat ions for the unreconstructed (1 x 1) plane produced a compressive stre ss in one direction and a slight tension in the other. On the (111) su rface, isotropic and relatively low compressive stress values were fou nd. Present calculations indicate that atoms located only in a few tap layers have lateral excess stresses which vanish very quickly for the atoms of interior layers as depart form the exposed surface.