title: Theoretical strength and cleavage of diamond
abstract: The theoretical strength of diamond has been calculated for the <100>, <110>, and <111> directions using a first principles approach and is found to be strongly dependent on crystallographic direction. This elastic anisotropy, found at large strains, and particularly the pronounced minimum in cohesion in the <111> direction, is believed to be the reason for the remarkable dominance of the 111 cleavage plane when diamond is fractured. The extra energy required to cleave a crystal on planes other than 111 is discussed with reference to simple surface energy calculations and also the introduction of bond-bending terms.
authors.affiliation: Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 OHE, United Kingdom.
authors.initials: RH
authors.lastname: Telling
authors.initials: CJ
authors.lastname: Pickard
authors.initials: MC
authors.lastname: Payne
authors.initials: JE
authors.lastname: Field