Читать книгу Encyclopedia of Glass Science, Technology, History, and Culture - Группа авторов - Страница 318

The statically arrangement of structural units for B₂O₃ glass and the dynamically arrangement of structural units for SiO₂ glass represent new insights on glass structure provided by MD simulations, in these cases, by the TAD, which escape any experimental determinations. These two examples thus illustrate the complementary nature of numerical simulations and experimental studies of glass structure. When the history of structural studies on glass is looked back on, it is clear that both diffraction and spectroscopic studies have made fundamental contributions to the construction of structural models. The RDF or the PDF can indeed be readily calculated from the Fourier transform of experimental X‐ray, neutron, or electron diffraction data (Chapter 2.2). Because this type of information represents averaged one‐dimensional structural data, however, there is always some arbitrariness when reconstructing the actual three‐dimensional configuration in which one is interested.

Other probes such as IR, Raman, or NMR spectroscopies can provide information only on short‐range order in glass structure. In contrast, atomistic simulations do provide realistic three‐dimensional configuration directly as long as an appropriate atomistic model is employed. One could confidently argue that a structural model of glass is reliable when the model matches the results of both experiments and atomistic simulations. In summary, the relation between atomistic simulation and experiment is complementary because both methodologies provide insights on different aspects of glass structure. Atomistic simulations nonetheless possess two other advantages over experimental methods. The first is that they can determine three‐dimensional configurations from short‐ to medium‐range order extending up to the size of cell length (10–100 nm). The second is that a very broad range of atomistic simulations become possible as soon as an appropriate simulation model is established. For example, it is easy to change external conditions such as temperature, pressure, or other external forces to investigate their effects on structure. And physical and chemical properties can be readily derived from the potential‐energy and structural models with standard statistical mechanical methods.