二元钠硅酸盐的精细结构和 29Si化学位移的从头计算研究

本文应用量子化学从头计算方法研究二元钠硅酸盐的精细结构，对典型的系列二元钠硅酸盐团簇模型采用闭壳层Hartree-Fock(RHF)方法和基组6-31G(d)优化构型，并计算了硅酸盐团簇中 ²⁹Si核磁共振化学位移δ_iso^Si，用硅氧四面体应力指数这一精细结构参数分析了计算得到的δ_iso^Si数值。同时对 ²⁹Si核磁共振化学位移δ_iso^Si的计算值和实验值进行比较，并讨论了两者间在数值上存在的差异。研究表明， ²⁹Si核磁共振化学位移与硅酸盐的精细结构密切相关，这说明硅酸盐的宏观物理和化学性质可能主要依赖于其精细结构而非初级结构单元-硅氧四面体。

Ab Initio of Fine Structure and 29Si Chemical Shift of Binary Sodium Silicate

Ab initio calculation method of quantum chemistry was used to optimize several typical model binary sodium silicate clusters under restricted Hartree-Fock method with 6-31G(d) basis sets. ²⁹Si chemical shifts of NMR of those model clusters were also calculated and evaluated with the concept of fine micro-structure. The calculated data were compared with the experimental NMR results and the discrepancy was discussed. It shows that ²⁹Si chemical shift of NMR depends closely on environmental fine micro-structure. It can be inferred that macro physical and chemical properties of silicates might be predominantly determined by fine micro-structure instead of crude SiO₄ tetrahedron as primary micro-structure.