AI 中文总结
研究碱金属阳离子对水合双电子结构和反应性的影响，采用从头算分子动力学模拟，发现阳离子使双电子回转半径增加，形成特定排列，导致O-H键伸长，且可能抑制其反应性。
AI 中文摘要
当碱金属溶解在水中达到足够高浓度时，具有相反自旋的水合电子会配对形成双电子。由于这些体系反应剧烈甚至爆炸，实验研究具有挑战性，而模拟为表征水合双电子的结构、反应性及碱金属阳离子的影响提供了可能。本文进行了有无明确Li⁺或Cs⁺抗衡离子的水合双电子的从头算分子动力学模拟。结果表明，阳离子使双电子回转半径增加约10%并形成特定阳离子 - 双电子排列，还导致第一壳层中朝向双电子的O - H键显著伸长，且在模拟时间尺度上，金属阳离子可能抑制水合双电子的反应性。
英文摘要
Hydrated electrons of opposite spins pair to form dielectrons at sufficiently high concentrations that can be achieved by dissolution of alkali metals in water. While experimental investigations of these systems are challenging due to their vigorous, even explosive, reactivity, simulations open the possibility to characterize the structure and reactivity of hydrated dielectrons and the effects of alkali cations thereon. Here, we present ab initio molecular dynamics simulations of a hydrated dielectron without or with explicit Li$^+$ or Cs$^+$ counterions. While the overall solvation structure is preserved in all these systems, the presence of cations has a distinct effect of increasing the dielectron gyration radius by about 10% and forming cation-specific cation-dielectron arrangements. Moreover, analysis of water bond lengths reveals in all studied systems a substantial elongation of first-shell O-H bonds oriented toward the dielectron, providing a structural explanation for vibrational red-shifts observed in resonance Raman measurements. Finally, at the 10 ps simulation timescale, rare reactive events were observed, albeit only for the system without metal cations, where hydride intermediates stable on picosecond timescales were identified. These observations also suggest that on the investigated timescales, metal cations may suppress hydrated dielectron reactivity.
