By using the embedded atom method interatomic potential, all of the  < 50 tilt boundaries of hexagonal close-packed samples with the [00•1] orientation were calculated by means of molecular statics techniques. On the basis of the atomic-position analysis, the structural units of dislocation cores were identified. It was found that the atoms at the interfaces tended to form perfect regions and special dislocation cores in the form of a tetrahedron and 3 conjoined irregular tetrahedra. The larger the perfect regions in one period, the lower were the grain boundary energies. It was found that the atomic structures of high-angle (> 10) tilt boundaries, with  = 19 or 7, were similar to those of low-angle boundaries ( = 37). For each of the boundaries, the atomic positions along [0001] were not changed during the relaxation procedure.

Y.C.Wang, H.Q.Ye: Philosophical Magazine A, 1997, 75[1], 261-72