Theoretical Studies of Structure and Spectra of Glasses

玻璃结构和光谱的理论研究-量子化学 在从头算Hartree-Fock Self水平上的化学方法， 一致场分子轨道理论将被应用于一个 玻璃科学中的一些问题。 基本目标是 描述了物种的短程和中程秩序， 通过计算玻璃的几何形状、能量学和 光谱，并与实验进行比较。 各种样品的NMR谱 玻璃中的物种将计算几个短距离 有序物种，例如，硼氧环和硅酸盐四面体 各自的眼镜。 结构和光谱特性作为一个 电荷状态和聚合度的函数将是 计算以帮助监测溶胶-凝胶反应。 最后， 将发展计算氧的极化率的方法 在各种环境中发现的眼镜，并计算光谱 自由和络合探针离子的能量，用于评估 玻璃中不同氧化环境的光学碱度。 该提案将由DMR材料理论（67%）和 物理化学（33%）。 %%% 人们曾一度认为，结晶和玻璃状固体 在结构上有很大的不同，晶体既具有短 以及长程有序和具有任何有意义的有序的玻璃 只有在地方层面才有意义。 现在看来， 在许多情况下，玻璃具有基本的中程有序，即， 在长度尺度上对应于几个分子单位的顺序。 增加对本地和中程订单类型的了解 存在于玻璃中，以及这种秩序对玻璃的影响。 玻璃的特性将使制造玻璃成为可能 使用非经验原子论方法定制属性。 将量子化学方法应用于这一问题是我们的目标 该提案将由DMR材料理论共同资助 (67%）和化学物理化学（33%）。

Theoretical Studies of Structure and Spectra of Glasses - Quantum- chemical methods at the level of ab initio Hartree-Fock Self- Consistent Field Molecular Orbital Theory will be applied to a number of problems in glass science. The basic goal will be to characterize both the short and medium range order of species in glasses by calculating values for their geometries, energetics, and spectra, and comparing with experiment. NMR spectra of various species in glasses will be calculated for several short range ordered species, e.g., boroxol rings and silicate tetrahedra in their respective glasses. Structural and spectral properties as a function of charge state and degree of polymerization will be calculated to assist in monitoring sol-gel reactions. Finally, methods will be developed to calculate polarizabilities of oxygen in various environments found in glasses and to calculate spectral energies for free and complexed probe ions used to evaluate the optical basicities of different oxidic environments in glasses. This proposal will be cofunded by DMR-Materials Theory (67%) and by CHEM-Physical Chemistry (33%). %%% It was once thought that crystalline and glassy solids were very much different structurally, with crystalls possessing both short and long range order and glasses possessing order in any meaningful sense only at the local level if at all. It now seems clear that in many cases glasses possess substantial medium range order, i.e., order on a length scale corresponding to several molecular units. Increased knowledge of the types of local and medium range order existing in glasses and the influence of such order upon the properties of the glass will make it possible to create glasses with tailored properties using nonempirical atomistic approaches. Application of quantum chemical methods to this problem is the goal of this proposal, which will be cofunded by DMR-Materials Theory (67%) and by CHEM-Physical Chemistry (33%).