Marti J
Departament de Fisica i Enginyeria Nuclear, Universitat Politecnica de Catalunya, B5-206 Campus Nord, 08034 Barcelona, Catalonia, Spain* and Department of Chemistry, University of California, Berkeley, California 94720-1460, U.
Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics. 2000 Jan;61(1):449-56. doi: 10.1103/physreve.61.449.
Dynamic properties of supercritical water at temperatures between 573 and 773 K and densities between 0.49 and 0.83 g/cm(3) have been investigated by molecular dynamics simulation and compared to states located on the vapor-liquid coexistence curve. A flexible simple point charge potential has been assumed for interactions in the subcritical states, whereas a reparameterization of that model has been performed to model the supercritical states. The hydrogen bonding structure and the diffusion coefficients in an ensemble of simulated states were previously analyzed and a good agreement with available experimental data was found. Dynamic properties of hydrogen bonding like the bond lifetimes and the influence of hydrogen bonds in the vibrational spectra are discussed along a range of simulation conditions. A nonlinear behavior of the hydrogen-bond lifetime as a function of temperature is observed in subcritical water whereas a linear dependence is found in supercritical water. Special attention is paid to the intermolecular vibrational spectrum (10-400 cm(-1)). It has been observed that the mode centered at 200 cm(-1), attributed to the intermolecular O-O stretching vibration in the ambient state remains active in the supercritical states.
通过分子动力学模拟研究了温度在573至773 K之间、密度在0.49至0.83 g/cm³之间的超临界水的动力学性质，并与位于气液共存曲线上的状态进行了比较。对于亚临界状态下的相互作用，采用了灵活的简单点电荷势，而对该模型进行了重新参数化以模拟超临界状态。之前对模拟状态集合中的氢键结构和扩散系数进行了分析，发现与现有实验数据吻合良好。在一系列模拟条件下，讨论了氢键的动力学性质，如键寿命以及氢键在振动光谱中的影响。在亚临界水中观察到氢键寿命随温度呈非线性行为，而在超临界水中发现呈线性依赖关系。特别关注分子间振动光谱（10 - 400 cm⁻¹）。已观察到，在环境状态下归因于分子间O - O伸缩振动、中心位于200 cm⁻¹的模式在超临界状态下仍然活跃。
