Bonding Analysis of Ab Initio Electronic Wave Functions in Molecules

爱荷华州立大学的Klaus Ruedenberg和Mark Gordon得到了化学系化学理论、模型和计算方法计划的一项奖励的支持，他们开发了一种一般方法，根据单个原子的变形和不同原子之间的相互作用产生的贡献来解决任何分子和相互作用分子之间的键能。后者进一步通过归因于不同的物理相互作用的贡献来解决，即。准经典静电相互作用、干涉相互作用和电荷转移效应。这种分析是从精确的从头算能量表达式中提取出来的，通过转换成准原子轨道的基，而准原子轨道是从精确的从头算波函数本质上推导出来的。对于一些反应，研究了各种贡献及其动能和势能分量在建立化学键中的作用。在此基础上，确定了成键的概念特征，并建立了严格的从头计算基础，以确定不同成键模式之间的相似和区别。当前的量子化学可以产生在许多化学工作领域有价值和有用的定量信息和预测，而纯粹的实验方法无法提供这些信息和预测。这些能力是数学算法进步的结果，同时电子计算机的速度和存储能力也在稳步提高。然而，计算技术的日益复杂使人们极难理解原子之间键形成和断裂的物理原因，即使在简单和基本的化学反应中也是如此。这种缺乏物理洞察力的做法在数字运算方法和化学直觉之间造成了巨大的差距，这两种方法在两个世纪以来一直很好地服务于实验化学家，事实证明，两者之间的桥梁并不是微不足道的。本工作确定了这些复杂计算的物理内容，并提取了一种适合于化学推理的直观框架的对化学键的解释。以前未开发的化学有趣信息嵌入到准确的量子力学计算中，可以访问。

Klaus Ruedenberg and Mark Gordon of Iowa State university are supported by an award from the Chemical Theory, Models and Computational Methods program in the Chemistry division to develop a general method for resolving the bond energies in any molecule and between interacting molecules in terms of contributions that arise from the deformations of the individual atoms and from the interactions between different atoms. The latter are furthermore resolved in terms of contributions that are attributed to distinct physical interactions, viz. quasi-classical electrostatic interactions, interference interactions and charge transfer effects. The analysis is extracted from the accurate ab initio energy expression by transformation into a basis of quasi-atomic orbitals that are intrinsically deduced from the accurate ab initio wave function. The role of the various contributions and of their kinetic and potential energy components in the establishment of chemical bonding is investigated for a number of reactions. On this basis, conceptual characterizations of bonding are identified and a rigorous ab initio basis for similarities and distinctions between different bonding patterns is established.Current quantum chemistry can generate quantitative information and predictions that are valuable and useful in many areas of chemical work and that the purely experimental approach is unable to supply. These capabilities are the result of advances in mathematical algorithms in conjunction with the steady increase in the speed and storage capacity of electronic computers. The increasing complexity of the computational techniques has made it, however, extremely difficult to perceive the physical reasons why bonds form and break between atoms, even in simple and fundamental chemical reactions. This lack of physical insight has created a large gap between the number crunching approach and the chemical intuition that has served experimental chemists well for two centuries, and the bridging between the two has proved to be nontrivial. The present work identifies the physical contents of these complex calculations and extracts an interpretation of chemical bonding that can fit into the intuitive frame work of chemical reasoning. Previously untapped chemically interesting information, which is imbedded in accurate quantum mechanical computations, is made accessible.