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oe1(光电查) - 科学论文

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  • Medium range order and configurational entropy of vitreous silica

    摘要： Two potential sets and three thermodynamic regimes were utilized in molecular dynamics simulations in the preparation of the corresponding structures of vitreous silica. Medium range order characterized by means of basic ring distributions is robust to both thermodynamic conditions and/or potentials sets. A strong correlation between topology and geometry is demonstrated; the correlation is much stronger for simple clusters/small rings. Configurational entropy was evaluated by the ideal mixing of the structural units of the decomposed silica network. Entropy responds to alterations in the heating/cooling rates and its behaviour yields an excellent agreement with the experimental specific heat capacity drops observed at the glass transition. It is suggested the glass transition of the simulated glass should be identified with the change of entropy and not with a change of enthalpy as is conventionally done.

    关键词： medium range order,configurational entropy,vitreous silica,glass transition,molecular dynamics simulations

    更新于2025-09-04 15:30:14

  • The effect of the medium-range configuration on the atomistic fracture behaviour of vitreous silica

    摘要： Using molecular dynamics simulations, we prepare vitreous silica by quenching molten silica to ambient temperature. Varying the quenching rate, we show that the latter barely influences the short-range order, whereas the medium-range configuration is significantly affected. We subject the prepared silica specimens to tension until fracture occurs and demonstrate the effect on the material behaviour. We evaluate the medium-range configuration in terms of the ring statistics of the glass network structure. Linking the ring statistics with the deformation and fracture behaviour of vitreous silica, we provide a topologically motivated explanation of the material behaviour.

    关键词： quenching rate,fracture behaviour,vitreous silica,medium-range configuration,molecular dynamics

    更新于2025-09-04 15:30:14