  The pressure-induced structural transition from graphite to diamond is
investigated by semi-empirical molecular dynamics simulation. The result shows
that the graphite-diamond transition is a cooperative process with large
fluctuation. We studied catalyst-aided effect by introducing a simple model
into a conventional tight binding Hamiltonian of carbon bonding structure. The
obtained result suggest that weak disorder in graphite not only accelerate the
transition to cubic diamond but also will be an origin of high-pressure
polymorph of carbon, such as hexagonal diamond.
