  A hybrid scheme between large-scale electronic structure calculations is
developed and applied to nanocrystalline silicon with more than 10$^5$ atoms.
Dynamical fracture processes are simulated under external loads in the [001]
direction. We shows that the fracture propagates anisotropically on the (001)
plane and reconstructed surfaces appear with asymmetric dimers. Step structures
are formed in larger systems, which is understood as the beginning of a
crossover between nanoscale and macroscale samples.

Materials Science