  The 10-nm-scale structure in silicon cleavage is studied by the quantum
mechanical calculations for large-scale electronic structure. The cleavage
process on the order of 10 ps shows surface reconstruction and step formation.
These processes are studied by analyzing electronic freedom and compared with
STM experiments. The discussion presents the stability mechanism of the
experimentally observed mode, the $(111)$-$(2 x 1)$ mode, beyond the
traditional approach with surface energy. Moreover, in several results, the
cleavage path is bent into the experimentally observed planes, owing to the
relative stability among different cleavage modes. Finally, several common
aspects between cleavage and other phenomena are discussed from the viewpoints
of the nonequilibrium process and the 10-nm-scale structure.
