Molecular dynamics study on local structure of molten silicon

A modified Tersoff potential developed by extending atomic interaction dist ance has been applied to simulating the properties of liquid silicon with m olecular dynamics. The radical distribution functions with coordination num ber 6.9 and bond length 0.254 nm from the simulation are in good agreement with the experimental results from X-ray diffraction and neutron scattering . The configurations simulated indicate that a chain-network structure is f ormed among silicon atoms in liquid silicon, and a majority of atoms remain tetrahedral local structure with near-neighbour atoms. The presence of two peaks, similar to 57 degrees and similar to 102 degrees, in bond angle pro bability distribution indicates a very complicated structure in liquid sili con. Based on the instantaneous configurations given by the simulation, the local structures in liquid states have been studied with bond-order parame ter method. The results show there are similar to 82% tetrahedron structure s in the near-neighbour structures in liquid state and the square deviation of bond-orientational fluctuation is about 5.2 degrees. The results also s how that except thericosahedron structure, the non-tetrahedral structures m ay include some other near-neighbour structures.