电子是通过共价共享实现水合的？
Is the Electron Hydrated Through Covalent Sharing?
AI总结：
本文通过从头算方法揭示水合电子并非静电捕获于空腔，而是通过共振附着形成共价离域，从而解释其高结合能和激发态特征。
AI中文摘要：
水合电子（$e_{aq}^-$）是辐射化学中的关键物种，传统上被建模为限制在溶剂空腔内的内部电子，并通过静电相互作用稳定。然而，这一图像无法解释其高结合能和离散激发态，因为空腔缺乏足够的偶极强度来支持深电子约束。利用能够捕捉自由电子与水之间共振相互作用的\textit{从头算}方法，我们表明水合电子是通过共价离域稳定的。现有方法将其误表示为空腔内的静电捕获——这种解释源于预先束缚电子的假设，并忽略了自由电子与水初始相互作用的共振特性。我们的结果表明，电子通过共振附着到邻近水分子上形成瞬态负离子分子态，在其中被初始捕获，并通过由$a_1$价轨道叠加形成的分子间键合网络在其上离域。这种共价离域产生了类似空腔的结构，而无需静电捕获，并自然地解释了观察到的光谱特征，包括更高节激发态和增强的结合能。总之，空腔形成是由\textit{缔合电子附着（AEA）}引发的——这是一种由自由电子与其邻近水分子之间的共振相互作用驱动的分子过程，在此过程中电子与其共价共享——发生在自由电子完全溶剂化之前的能量耗散阶段。
英文摘要：
The hydrated electron ($e_{aq}^-$), a key species in radiation chemistry, is traditionally modeled as an interior electron confined within a solvent cavity and stabilized by electrostatic interactions. However, this picture fails to account for its high binding energy and discrete excited states, as the cavity lacks sufficient dipole strength to support deep electronic confinement. Using \textit{ab initio} methods that capture resonant interactions between the free electron and water, we show that the hydrated electron is stabilized through covalent delocalization. Existing approaches misrepresent this as electrostatic trapping within a cavity -- an interpretation rooted in assumptions of a pre-bound electron and the omission of the resonant character of the initial interaction between the free electron and water. Our results reveal that the electron forms transient negative ion molecular states through resonant attachment to neighboring water molecules, where it is initially captured, and delocalizes over them via an intermolecular bonding network formed by the superposition of $a_1$ valence orbitals. This covalent delocalization yields cavity-like structures without requiring electrostatic trapping and naturally explains observed spectral features, including higher-nodal excited states and enhanced binding energies. In short, cavity formation is initiated by \textit{associative electron attachment (AEA)} -- a molecular process driven by a resonant interaction between the free electron and its neighboring water molecules, and wherein the electron becomes covalently shared to them -- during the energy dissipation phase of the free electron preceding full solvation.
