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arXiv 1509.00295physics.chem-ph
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氢键的物理性质

Physical Nature of Hydrogen Bond

I. V. Zhyganiuk, M. P. Malomuzh

摘要:

讨论了氢键(H键)的物理性质和正确定义。分析了氢键对水的热力学、动力学和光谱性质的影响。氢键作为水分子之间的尖锐定向和饱和桥的传统模型与水的比容、蒸发热、自扩散和运动剪切粘度系数的行为不相容。另一方面,本文还指出,水分子的偶极矩变化和羟基的价振动频移完全可以用氢键静电模型来解释。同时,水在液态和汽态下的热容随温度的变化关系清楚地证明了弱氢键的存在。对水二聚体的分析表明,弱氢键对其基态能量的贡献比水分子间静电相互作用的能量约低4--5倍。得出了氢键在其他情况下具有相同性质的结论。

英文摘要:

The physical nature and the correct definition of hydrogen bond (H-bond) are considered.\,\,The influence of H-bonds on the thermodynamic, kinetic, and spectroscopic properties of water is analyzed.\,\,The conventional model of H-bonds as sharply directed and saturated bridges between water molecules is incompatible with the behavior of the specific volume, evaporation heat, and self-diffusion and kinematic shear viscosity coefficients of water. On the other hand, it is shown that the variation of the dipole moment of a water molecule and the frequency shift of valence vibrations of a hydroxyl group can be totally explained in the framework of the electrostatic model of H-bond.\,\,At the same time, the temperature dependences of the heat capacity of water in the liquid and vapor states clearly testify to the existence of weak H-bonds.\,\,The analysis of a water dimer shows that the contribution of weak H-bonds to its ground state energy is approximately 4--5 times lower in comparison with the energy of electrostatic interaction between water molecules.\,\,A conclusion is made that H-bonds have the same nature in all other cases where they occur.

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