Yoon Tae Jun, Patel Lara A, Ju Taeho, Vigil Matthew J, Findikoglu Alp T, Currier Robert P, Maerzke Katie A
Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545, USA.
Phys Chem Chem Phys. 2020 Jul 22;22(28):16051-16062. doi: 10.1039/d0cp02288h.
Molecular dynamics (MD) simulations to understand the thermodynamic, dynamic, and structural changes in supercritical water across the Frenkel line and the melting line have been performed. The two-phase thermodynamic model [J. Phys. Chem. B, 2010, 114(24), 8191-8198] and the velocity autocorrelation functions are used to locate the Frenkel line and to calculate the thermodynamic and dynamic properties. The Frenkel lines obtained from the two-phase thermodynamic model and the velocity autocorrelation criterion do not agree with each other. Structural characteristics and the translational diffusion dynamics of water suggest that this inconsistency could arise from the two oscillatory modes in water, which are associated with the bending of hydrogen bonds and intermolecular collisions inside the first coordination shell. The overall results lead us to conclude that the universality of the Frenkel line as a dynamic crossover line from rigid to nonrigid fluids is preserved in water.
为了理解超临界水在弗伦克尔线和熔点线处的热力学、动力学和结构变化，已经进行了分子动力学（MD）模拟。采用两相热力学模型[《物理化学杂志B》，2010年，114(24)，8191 - 8198]和速度自相关函数来确定弗伦克尔线，并计算热力学和动力学性质。从两相热力学模型和速度自相关准则得到的弗伦克尔线彼此不一致。水的结构特征和平动扩散动力学表明，这种不一致可能源于水中的两种振荡模式，它们与氢键的弯曲以及第一配位层内的分子间碰撞有关。总体结果使我们得出结论，弗伦克尔线作为从刚性流体到非刚性流体的动态交叉线的普遍性在水中得以保留。
