Molecular dynamics study on local structure of molten silicon

A modified Tersoff potential developed by extending atomic interaction distance has been applied to simulating the properties of liquid silicon with molecular dynamics. The radical distribution functions with coordination number 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 formed 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 probability distribution indicates a very complicated structure in liquid silicon. Based on the instantaneous configurations given by the simulation, the local structures in liquid states have been studied with bond-order parameter method. The results show there are similar to 82% tetrahedron structures in the near-neighbour structures in liquid state and the square deviation of bond-orientational fluctuation is about 5.2 degrees. The results also show that except thericosahedron structure, the non-tetrahedral structures may include some other near-neighbour structures.