From: David Vanderbilt <dhv@physics.rutgers.edu> Date: Tue, 23 Jun 1998 18:02:42 GMT (53kb)
Authors:
R.W. Nunes,
J. Bennetto,
David Vanderbilt (Department of Physics and Astronomy, Rutgers University)
Comments: 4 pages, two-column style with 1 postscript figure embedded. Uses
REVTEX and epsf macros. Also available at
this http URL
Subj-class: Materials Science
We investigate the energetics of the single-period and double-period core reconstructions of the 90-degree partial dislocation in the homopolar semiconductors C, Si, and Ge. The double-period geometry is found to be lower in energy in all three materials, and the energy difference between the two geometries is shown to follow the same trends as the energy gap and the stiffness. Both structures are fully reconstructed, consisting entirely of fourfold coordinated atoms. They differ primarily in the detail of the local strains introduced by the the two reconstructions in the core region. The double-period structure is shown to introduce smaller average bond-length deviations, at the expense of slightly larger average bond-angle bending distortions, with respect to the single-period core. The balance between these two strain components leads to the lower energy of the double-period reconstruction.