A novel interatomic tnil ngy fnction is proposed for cnnd systems composed of silicon and oxygen atoms,from SiO2 to Si crystal. The potential function is an extention of the Stillinger-Weber potential, which was originally desingned for pure Si systems. All parameters in the potential function were determined based on ab initio molecular orbital calculations of small clusters. Without any adjustment to empirical data, the order of stability of five silica polymorphs is correctly reproduced. This potential realizes a large-scale modeling of SiO2/Si interface structures on average workstation computers.
Fig.1 Structural energies vs (a)Si-O bond length (b)-(d) bond-angles of cluster model as shown in insets. Plots are calculated energies by Hartree-Fock molecular orbital theory. Solid curves are fitted curves by the new potential function.
Fig.2 SiO2/Si interface model with 3904 atoms, constructed by using the new potential function. Gray and black spheres represent Si and O atoms, respectively.