大規模複雑系に適用可能な新規量子化学計算手法の開発と応用

我们研究了离子液体的结构以及电子性质和动力学特性的快速，最先进的半经验量子化学模拟方法的帮助下。在开始时，进行了相当大的努力，以优化现有算法的实现，使它们适用于现代并行计算机架构，并使快速生成的离子液体分子簇具有不同的约束。借助该算法，生成了由甲基、乙基和丁基甲基咪唑阳离子和硝酸根阴离子组成的离子液体分子簇的结构，并制备了用于后续量子化学研究的分子簇.所有结构都可以使用片段-分子轨道密度-功能紧束缚方法成功优化。通过与现有的模拟研究和实验进行比较，验证了这些结构的有效性后，我们进行了电子结构计算。首先，我们研究了不同烷基侧链对离子液体结构的影响，以及对氧化还原性能的影响，特别是HOMO-LUMO间隙。采用密度泛函紧束缚方法对离子液体小分子团簇进行了分子动力学模拟。为了使更有效的模拟，扩展的拉格朗日协议可以应用到调查系统。这种计算的结果提供了深入了解离子液体的结构和动力学，关于这一主题的出版物正在筹备中。

We investigated structural as well as electronic properties and dynamic features of ionic liquids with the help of fast, state-of-the-art semi-empirical quantum-chemical simulation methods. At the beginning, considerable efforts were undertaken to optimize implementations of existing algorithms to make them applicable to modern parallel computer architecture and enable a fast generation of molecular clusters of ionic liquids with varying constraints. With the help of this algorithm, structures of molecular clusters of ionic liquids consisting of methyl-, ethyl- and butylmethylimmidazolium cations and nitrate anions were generated and prepared for subsequent investigation by quantum-chemical methods. All structures could be successfully optimized using the fragment-molecular-orbital density-functional tight-binding method. After the validity of these structures were verified by comparing to existing simulation studies and experiments, we proceeded to electronic structure calculations. First, we investigated the effect of different alkyl-side chains on the structures of the ionic liquids as well as the effect on the redox properties, especially the HOMO-LUMO gap. On small-sized molecular clusters of ionic liquids, molecular dynamics simulation using the density-functional tight-binding method was performed. To enable more efficient simulations, the extended Lagrangian protocol can be applied to the investigated systems. The results of such calculations provide insight into the structure and dynamics of ionic liquids and a publication on this topic is in preparation.