水分子聚合物的电荷转移能量由分子束散射实验,电荷位移分析和ab initio计算揭示出来
Leonardo Belpassi1, Michael L Reca, Francesco Tarantelli
1Dipartimento di Chimica, Università di Perugia, 06123 Perugia, Italy. belp@thch.unipg.it
Journal of the American Chemical Society
|September 1, 2010
概括
由于显著的电荷转移 (CT),水相互作用比预期的要强. 这种电荷转移,水作为电子捐赠者或接受者,解释了分子相互作用中观察到的稳定能.
科学领域:
- 物理化学 物理化学
- 化学物理 化学物理
- 量子化学 是一个量子化学.
背景情况:
- 分子间力量控制着分子相互作用.
- 准确的潜在能量表面 (PES) 对于理解化学反应和材料特性至关重要.
- 水-H(2) 系统是结合和涉及水的相互作用的基本模型.
研究的目的:
- 为了实验性地测量水-H2碰撞的积分截面.
- 从理论上研究电子电荷移位及其在水-H2相互作用中的作用.
- 开发一种理论模型来解释观察到的分子间潜力.
主要方法:
- 分子束散射实验以获得整体横截面.
- 在潜在能量表面 (PES) 上对电子电荷位移的理论分析.
- 使用结合集群单双与扰乱三倍 (CCSD(T)) 方法和大基础集的初始计算.
主要成果:
- 实验数据表明,水-H(2) 潜力的吸引成分比单独的分散和感应力预测的强度大约30%.
- 理论分析显示,在水-H2相互作用过程中,有显著的电荷转移 (CT).
- 在不同距离的稳定能量和CT大小之间发现了定量相关性.
- 开发的理论模型准确地复制了CCSD (T) 级 PES 部分.
结论:
- 电荷转移 (CT) 是水-H2分子间相互作用的显著和立体特异性贡献者.
- 根据水的方向,水可以充当电子捐赠者或接受者.
- 与CT相关的能量稳定约为每电子转移2.5 eV.
- 这些发现对理解水在化学中的作用有着广泛的意义.
相关概念视频
Hydrogen Bonds
A hydrogen bond is formed when a weakly positive hydrogen atom already bonded to one electronegative atom (for example, the oxygen in the water molecule) is attracted to another electronegative atom from another polar molecule, such as water (H2O), hydrogen fluoride (HF), or ammonia (NH3). The huge electronegativity difference between the H atom (2.1) and the atom to which it is bonded (4.0 for an F atom, 3.5 for an O atom, or 3.0 for an N atom), combined with the very small size of an H atom...
Hydrogen Bonds
Hydrogen BondsHydrogen bonds are weak attractions between atoms that have formed other chemical bonds. One of these atoms is electronegative, like oxygen, and has a partial negative charge. The other is a hydrogen atom that has bonded with another electronegative atom and has a partial positive charge.Hydrogen Bonds Control the World!Because hydrogen has very weak electronegativity when it binds with a strongly electronegative atom, such as oxygen or nitrogen, electrons in the bond are...
Introduction to Chemical Bonds
Chemical Bonds
The electrons of the outermost energy level determine the energetic stability of the atom and its tendency to form chemical bonds with other atoms. The innermost electron shell has a maximum capacity of two electrons, but the next two electron shells can each have a maximum of eight electrons. This is known as the octet rule, which states that, with the exception of the innermost shell, atoms are most stable energetically when they have eight electrons in their valence shell, the...
The electrons of the outermost energy level determine the energetic stability of the atom and its tendency to form chemical bonds with other atoms. The innermost electron shell has a maximum capacity of two electrons, but the next two electron shells can each have a maximum of eight electrons. This is known as the octet rule, which states that, with the exception of the innermost shell, atoms are most stable energetically when they have eight electrons in their valence shell, the...
Van der Waals Interactions
Atoms and molecules interact with each other through intermolecular forces. These electrostatic forces arise from attractive or repulsive interactions between particles with permanent, partial, or temporary charges. The intermolecular forces between neutral atoms and molecules are ion–dipole, dipole–dipole, and dispersion forces, collectively known as van der Waals forces.Polar molecules have a partial positive charge on one end and a partial negative charge on the other end of the molecule,...
Intermolecular Forces
Atoms and molecules interact through bonds (or forces): intramolecular and intermolecular. The forces are electrostatic as they arise from interactions (attractive or repulsive) between charged species (permanent, partial, or temporary charges) and exist with varying strengths between ions, polar, nonpolar, and neutral molecules. The different types of intermolecular forces are ion–dipole, dipole–dipole, hydrogen bonds, and dispersion; among these, dipole–dipole, hydrogen bonds, and dispersion...
Electrochemical Systems
Electrochemical systems provide a fascinating insight into the dynamic interplay of charged species within various phases. One notable example is the interaction between a membrane permeable to K⁺ ions but not to Cl⁻ ions, separating an aqueous KCl solution from pure water. As K⁺ ions diffuse through the membrane, they generate net charges on each phase, leading to a potential difference between them.Similarly, when a piece of Zn is immersed in an aqueous ZnSO₄ solution, the Zn metal, composed...


