The application of the molecular dynamics simulation based one the molecular orbital calculation to the vitreous state

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The molecular dynamics (MD) simulation with electronic state, which was calculated by use of molecular orbital method, was produced and the vitreous state was simulation by this method.. The potential energies of the clusters were calculated using GAMESS, which is one of the programs for ab initio molecular orbital method. By decomposing the potential energies in the potential function of the atomic distance and the bond angle, the parameter of the potential function was estimated. We applied this method to SiO_2, B_2O_3 and P_2O_5 systems.The parameters of the function of the atomic distance and bond angle could be obtained. (1)The radial distribution curves calculated from the structural models obtained from the molecular dynamics simulation using the obtained potentials and they were compared with the observed ones. (2)The vibrational spectra were calculated from the trace of the coordinates of the simulation. We also calculated radial distribution curves and vibrational spectra from the structural models based on TTAM and BKS potentials. The agreement of the radial distribution curves and vibrational modes and wavenumber, could be obtained from the structural models of our simulations. However, it is difficult to find that the potential parameters. The radial distribution curves and vibrationl frequencies calculated using the parameters be agreed with the observed ones simultaneously. The two-body potentials for B2O3 and P2O5 systems were evaluated. It was confirmed that the vitreous state using the potential parameters and that the structure models, which correspond to the crystal structure could be obtained.