Various symmetrical tilt grain boundary structures were analyzed by using a transferable tight-binding C potential. By using tight-binding molecular dynamics methods, it was possible to simulate several 1000 atoms and permit the examination of low-angle boundaries with large periodicities. It was found that the lowest-energy structure was the {111} twin boundary; which corresponded to the  = 3, 70.53 grain boundary. For angles of less than 70.53, the boundaries comprised a series of b = <01¯1> edge dislocations. The core structures of these dislocations contained 5-atom and 7-atom rings. The tight-binding energies for these low-angle structures exhibited trends which were similar to those found using a Tersoff potential. Both models gave results that were consistent with linear elasticity theory. In the case of high-angle {211} and {311} boundaries, the tight-binding model predicted the occurrence of reconstruction along the <011> direction, in order to eliminate dangling bonds.

J.R.Morris, C.L.Fu, K.M.Ho: Physical Review B, 1996, 54[1], 132-8