INTERPLANAR RELAXATION AT THE (0001) SURFACE OF BE

Using ab initio many body interatomic potential and molecular dynamics approach we have calculated the interplanar relaxation at the (0001) surface of Be. A slab of 392 atoms in seven layers with periodic boundary conditions was used to model the surface. All but two layers were allowed to relax. The results indicate an expansion of 5.9% of the top two layers. The relaxation between the second and third layers is considerably smaller, namely 0.9%, while the remaining layers do not relax at all. Our results are in excellent agreement with the experiment and provide additional insight into the nature of bonding between atoms with low coordination.