Hakem Ilhem F, Boussaid Abdelhak, Benchouk-Taleb Hafida, Bockstaller Michael R
Department of Materials Science and Engineering, Cargenie Mellon University, 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213, USA.
J Chem Phys. 2007 Dec 14;127(22):224106. doi: 10.1063/1.2804418.
We present a lattice model to describe the effect of isotopic replacement, temperature, and pressure changes on the formation of hydrogen bonds in liquid water. The approach builds upon a previously established generalized lattice theory for hydrogen bonded liquids [B. A. Veytsman, J. Phys. Chem. 94, 8499 (1990)], accounts for the binding order of 1/2 in water-water association complexes, and introduces the pressure dependence of the degree of hydrogen bonding (that arises due to differences between the molar volumes of bonded and free water) by considering the number of effective binding sites to be a function of pressure. The predictions are validated using experimental data on the temperature and pressure dependence of the static dielectric constant of liquid water. The model is found to correctly reproduce the experimentally observed decrease of the dielectric constant with increasing temperature without any adjustable parameters and by assuming values for the enthalpy and entropy of hydrogen bond formation as they are determined from the respective experiments. The pressure dependence of the dielectric constant of water is quantitatively predicted up to pressures of 2 kbars and exhibits qualitative agreement at higher pressures. Furthermore, the model suggests a--temperature dependent--decrease of hydrogen bond formation at high pressures. The sensitive dependence of the structure of water on temperature and pressure that is described by the model rationalizes the different solubilization characteristics that have been observed in aqueous systems upon change of temperature and pressure conditions. The simplicity of the presented lattice model might render the approach attractive for designing optimized processing conditions in water-based solutions or the simulation of more complex multicomponent systems.
我们提出了一种晶格模型，用于描述同位素取代、温度和压力变化对液态水中氢键形成的影响。该方法基于先前建立的用于氢键液体的广义晶格理论[B. A. 韦茨曼，《物理化学杂志》94, 8499 (1990)]，考虑了水 - 水缔合复合物中1/2的键合顺序，并通过将有效键合位点的数量视为压力的函数，引入了氢键程度的压力依赖性（这是由于键合水和自由水的摩尔体积差异引起的）。利用关于液态水静态介电常数的温度和压力依赖性的实验数据对预测进行了验证。发现该模型在不使用任何可调参数的情况下，通过假设从各自实验中确定的氢键形成的焓和熵的值，能够正确地重现实验观察到的介电常数随温度升高而降低的现象。对水的介电常数的压力依赖性进行了定量预测，直至2千巴的压力，并在更高压力下表现出定性一致性。此外，该模型表明在高压下氢键形成随温度降低。该模型所描述的水结构对温度和压力的敏感依赖性，解释了在水体系中温度和压力条件变化时所观察到的不同溶解特性。所提出的晶格模型的简单性可能使该方法对于设计水基溶液中的优化加工条件或模拟更复杂的多组分系统具有吸引力。
