Molecular Orbital Theory of Molecules and Extended Structures

9408455霍夫曼·康奈尔大学在美国国家科学基金会理论和计算化学计划的支持下，扩展休克尔理论被应用于处理：(1)过渡金属碳化物、硼化物和硅化物，(2)铑卟啉配合物对CH和HH键的激活，(3)主基和过渡金属元素的四面体和正方形平面网络，(4)酶催化甲烷氧化为甲醇，以及(5)由互穿的类金刚石网络组成的新型超硬材料。我们将探索一些基于广义轨道布居的推测新成键概念。休克尔理论起源于分子量子力学的基本正确定律，但为了简化计算，进行了剧烈的近似，因此将这些方法应用于太大而不能用更严格的从头计算理论处理的分子系统是可行的。当明智地应用时，扩展的休克尔理论已被证明提供了对化学结构的可靠预测和对化学键原理的洞察。在这项研究项目中，休克尔理论被应用于广泛的化学问题，旨在发现具有不寻常的物理和化学性质的新材料，并加深对支配这些性质的化学原理的理解。

9408455 Hoffmann Cornell University In this research, supported by the NSF Theoretical and Computational Chemistry Program, extended Huckel theory is applied to treat: (1) transition metal carbides, borides, and silicides, (2) activation of CH and HH bonds by Rhodium porphyrin complexes, (3) tetrahedral and square-planar networks of main group and transition metal elements, (4) enzyme-catalyzed oxidation of methane to methanol, and (5) novel, super-hard materials consisting of interpenetrating diamond-like nets. Some speculative new bonding concepts based on generalized orbital populations will be explored. Huckel theory has its origin in the fundamentally correct laws of molecular quantum mechanics, but drastic approximations are made to simplify the computations so that it becomes feasible to apply these methods to molecular systems much too large to be treated by the more rigorous ab initio theories. When judiciously applied, extended Huckel theory has proved to provide reliable predictions of chemical structures and insight into the principles of chemical bonding. In this research project Huckel theory is applied to a broad range of chemical problems directed toward the discovery of new materials with unusual physical and chemical properties and a deeper understanding of the chemical principles which govern these properties.