Evolution of the electron density along reaction paths in presence and absense of external perturbation

近年来，一种名为分子中原子的量子理论(QTAIM)的化学理论在理论化学家中越来越受欢迎。该理论基于对分子电子密度的拓扑分析来解释和预测化学。电子密度可以从理论上计算，也可以在高分辨率X射线结晶学实验中进行实验观察(随后对数据进行特殊处理)。在QTAIM中，分子空间被划分为单独的原子区域，允许人们专注于分子中区域的*局部*性质，就像实验化学家对分子中特定功能基团的心理关注一样。到目前为止，QTAIM主要应用于基态平衡几何构型的分子。虽然这是一个重要的应用领域，但对于完全理解分子变化是不够的，分子变化是(生物)化学的很大一部分内容。本研究旨在研究分子变化过程中电子密度及其拓扑结构的变化：由于化学键的断裂和形成，或由于与金属的络合，或由于外部电磁场，或由于与溶剂的相互作用。我们将使用QTAIM来分析远离其平衡或过渡态几何构型的反应体系的电子密度。如果人们想要讨论反应性，用QTAIM方法探索完整的反应路径将产生必要的动力学和力学信息来补充静态图像。最近有少数孤立的论文提出了类似的主张，但这些论文缺乏专门研究计划的连贯性。这一建议旨在通过将这些想法应用于一系列重要问题来填补这一知识空白，这些问题的例子包括：i.金属离子和溶剂化对ATP(普遍存在的细胞燃料)水解的能量学的影响；ii.外部电磁场对生物膜脂质过氧化模型的影响；以及iii.外场对DNA质子跳跃的影响，这是一种公认的自发突变机制。

A theory of chemistry called the quantum theory of atoms in molecules (QTAIM) has become increasingly popular among theoretical chemists in recent years. The theory interprets and predicts chemistry on the basis of a topological analysis of the electron density of molecules. The electron density can be calculated from theory and can also be observed experimentally in high-resolution X-ray crystallographic experiments (followed by a special treatment of data). In QTAIM the molecular space is partitioned into separate atomic regions allowing one to focus on *local* properties of regions in a molecule just like the mental focus of an experimental chemist on a specific functional group in a molecule. So far QTAIM has been applied mainly to molecules in their ground state equilibrium geometries. While this is an important domain of application it is insufficient for a complete understanding of molecular change, change which is what a large part of (bio)chemistry is all about. This research aims at focusing on the evolution of the electron density and its topology during molecular change: Change due to the breaking and making of chemical bonds, or due to complexation with metals, or due to external electromagnetic fields, or due to interaction with solvent. We will use QTAIM to analyze the electron density of reacting systems far from their equilibrium or transition state geometries. This exploration of full reaction paths with the means of QTAIM will yield dynamical and mechanistic information necessary to complement the static picture if one wishes to discuss reactivity. A small number of very recent isolated papers advanced similar propositions, but these lack the coherence of a dedicated research program. This proposal aims at contributing in filling this gap in knowledge by applying these ideas to a selection of important problems, examples of which include: I. The effect of metal ions and solvation on the energetics of hydrolysis of ATP (the universal cellular fuel par excellence), II. The effects of external EM fields on models of the lipid peroxidation of biomembranes, and III. The effects of external fields on the proton hopping in DNA, an accepted mechanism of spontaneous mutation.