Classical two and three-body interatomic potentials for silicon.

We develop two and three-body classical interatomic potentials that model structural energies for silicon. These potentials provide a global fit to a database of first-principles calculations of the energy for bulk and surface silicon structures which spans a wide range of atomic coordinations and bonding geometries. This is accomplished using a new "separable" form for the 3- body potential that reduces the 3-body energy to a product of 2-body sums and leads to computations of the energy and atomic forces in n(2) steps as opposed to n(3) for a general 3-body potential. Simulated annealing is performed to find globally minimum energy states of Si-atom clusters with these potentials using a Langevin molecular dynamics approach.