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首页> 外文期刊>Journal of Non-Crystalline Solids: A Journal Devoted to Oxide, Halide, Chalcogenide and Metallic Glasses, Amorphous Semiconductors, Non-Crystalline Films, Glass-Ceramics and Glassy Composites >Atomic scale foundation of temperature-dependent bonding constraints in network glasses and liquids
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Atomic scale foundation of temperature-dependent bonding constraints in network glasses and liquids

机译：网络玻璃和液体中依赖温度的键合约束的原子尺度基础

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The behaviour of bonding constraints with temperature is analyzed from an atomic scale approach (Molecular Dynamics, MD) combined with partial bond angle distributions (PBAD). The latter allows to have access to the second moments (standard deviations) of the distributions. Large (small) standard deviations correspond to large (small) angular excursions around a mean value, and are identified as broken (intact) bond-bending constraints. A similar procedure is used for bond-stretching constraints. Systems examined include glassy and liquid disilicate 2SiO_2-Na_2O (NS2). In the glass, MD constraint counting closely matches Maxwell enumeration of constraints using the octet binding (8-N) rule. Results show that the standard deviations of the partial bond angle distributions increase with temperature and suggest a softening of bond-bending constraints. A bimodal bonding oxygen distribution is obtained for T> Tg, and the fraction of thermally activated broken bond-bending constraints computed as a function of temperature. Overall, these results provide a microscopic rationale for extending constraint counting from chalcogenides to complex oxides, and also a numerical basis for recent functional forms of temperature-dependent constraints proposed from energy landscape approaches.
机译：从原子尺度方法（分子动力学，MD）结合部分键角分布（PBAD）分析了键约束随温度的行为。后者允许访问分布的第二矩（标准偏差）。大（小）标准偏差对应于平均值附近的大（小）角度偏移，并被识别为折断（完整）的粘合弯曲约束。类似的过程用于绑定键约束。检查的体系包括玻璃态和液态二硅酸盐2SiO_2-Na_2O（NS2）。在玻璃中，MD约束计数使用八位字节绑定（8-N）规则与约束的Maxwell枚举紧密匹配。结果表明，部分键角分布的标准偏差随温度增加而增加，表明键合弯曲约束的软化。对于T> Tg，获得双峰键合氧分布，并且计算热活化断裂键合弯曲约束的分数作为温度的函数。总体而言，这些结果为将约束计数从硫族化物扩展到复杂氧化物提供了微观原理，并且为从能量景观方法提出的温度依赖约束的最新功能形式提供了数值基础。

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