Sodium borosilicate glasses Na₂O–B₂O₃–SiO₂ (NBS) are complex systems from a structural point of view. Three main building units are present: tetrahedral SiO₄ and BO₄ (B^IV) and triangular BO₃ (B^III). One of the salient features of these compounds is the change of the B^III/B^IV ratio with the alkali concentration, which is very difficult to capture in force fields-based molecular dynamics simulations. In this work, we develop a polarizable force field that is able to reproduce the boron coordination and more generally the structure of several NBS systems in the glass and in the melt. The parameters of the potential are fitted from density functional theory calculations only, in contrast with the existing empirical potentials for NBS systems. This ensures a strong improvement on the transferability of the parameters from one composition to another. Using this new force field, the structure of NBS systems is validated against neutron diffraction and nuclear magnetic resonance experiments. A special focus is given to the distribution of B^III/B^IV with respect to the composition and the temperature.

中文翻译：

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Na ₂ O–B ₂ O ₃ –SiO ₂玻璃的结构研究，采用分子极化力场进行分子模拟

从结构的角度来看，硼硅酸钠玻璃Na ₂ O–B ₂ O ₃ –SiO ₂（NBS）是复杂的系统。存在三个主要的建筑单元：四面体SiO ₄和BO ₄（B ^IV）和三角形BO ₃（B ^III）。这些化合物的显着特征之一是B ^III / B ^IV的变化比例与碱浓度成正比，这在基于力场的分子动力学模拟中很难捕获。在这项工作中，我们开发了一个可极化的力场，该力场能够重现硼的配位关系，更一般地说，它可以重现玻璃和熔体中几个NBS系统的结构。与NBS系统现有的经验电势相反，电势的参数仅根据密度泛函理论计算得出。这确保了参数从一种组合物到另一种组合物的可传递性的显着改善。利用这一新的力场，通过中子衍射和核磁共振实验验证了NBS系统的结构。特别关注B ^III / B ^IV的分配 关于组成和温度。