  In spite of remarkable developments in the field of advanced materials,
silicon remains one of the foremost semiconductors of the day. Of enduring
relevance to science and technology is silicon's nanomechanical behaviour
including phase transformation, amorphization and dislocations generation,
particularly in the context of molecular dynamics and materials research. So
far, comprehensive modelling of the whole cycle of events in silicon during
nanoscale deformation has not been possible, however, due to the limitations
inherent in the existing interatomic potentials. This paper examines how well
an unconventional combination of two well-known potentials - the Tersoff and
Stillinger-Weber - can perform in simulating that complexity. Our model
indicates that an irreversible deformation of silicon (Si-I) is set in motion
by a transformation to a non-diamond structure (Si-nd), and followed by a
subsequent transition to the Si-II and Si-XII' phases
(Si-I->Si-nd->Si-II->Si-XII'). This leads to the generation of dislocations
spreading outwards from the incubation zone. In effect, our simulations
parallel each and every one of the structural changes detected experimentally
in the deformed material. This includes both the sequence of phase transitions
and dislocation activity, which - taken together - neither the Tersoff nor
Stillinger-Weber, or indeed any other available Si interatomic potential, is
able to achieve in its own right. We have sought to additionally validate our
method of merging atomic potentials by applying it to germanium, and found it
can equally well predict germanium's transformation from a liquid to amorphous
state.
