A comparative study of fracture in Al: Quantum mechanical vs. empirical atomistic description
Q. Peng and G. Lu
Journal of the Mechanics and Physics of Solids, 59, 775-786 (2011).

ABSTRACT
A comparative study of fracture in Al is carried out by using quantum mechanical
and empirical atomistic description of atomic interaction at crack tip. The
former is accomplished with the density functional theory (OFT) based
quasicontinuum method (QCDFT) and the latter with the original quasicontinuum
method (EAM-QC). Aside from quantitative differences, the two descriptions also
yield qualitatively distinctive fracture behavior. While EAM-QC predicts a
straight crack front and a micro-twinning at the crack tip, QCDFT finds a more
rounded crack profile and the absence of twinning. Although many dislocations
are emitted from the crack tip in EAM-QC, they all glide on a single slip plane.
In contrast, only two dislocations are nucleated under the maximum load applied
in QCDFT, and they glide on two adjacent slip planes. The electron charge
density develops "sharp corners" at the crack tip in EAM-QC, while it is
smoother in QCDFT.