EMPIRICAL AND AB-INITIO LOCAL-DENSITY APPROXIMATION STUDIES OF AN MGO(100) TWIST GRAIN-BOUNDARY

A comparison of local-density approximation and classical potential ca lculations on the [001], Sigma=5 twist grain boundary in MgO shows tha t the complex structure observed in the defective grain boundary is ca used by a simple electrostatic effect. The electronic structure shows no states in the gap, suggesting that the 'defects' in the stable rela xed structure should be considered as structural elements rather than defects in the conventional sense.