Henao Andrés, Salazar-Rios Jorge Mario, Guardia Elvira, Pardo Luis C
Grup de Simulació per Ordinador en Matèria Condensada, Departament de Física, B4-B5 Campus Nord, Universitat Politècnica de Catalunya, E-08034 Barcelona, Catalonia, Spain.
Universidad de Manizales, Carrera 19a No. 19-03, 170001 Manizales, Caldas, Colombia.
J Chem Phys. 2021 Mar 14;154(10):104501. doi: 10.1063/5.0038762.
Water has a rich phase diagram with several crystals, as confirmed by experiments. High-pressure and high-temperature water is of interest for Earth's mantle and exoplanetary investigations. It is in this region of the phase diagram of water that new plastic crystal phases of water have been revealed via computer simulations by both classical forcefields and ab initio calculations. However, these plastic phases still remain elusive in experiments. Here, we present a complete characterization of the structure, dynamics, and thermodynamics of the computational plastic crystal phases of water using molecular dynamics and the two-phase thermodynamic method and uncover the interplay between them. The relaxation times of different reorientational correlation functions are obtained for the hypothetical body-centered-cubic and face-centered-cubic plastic crystal phases of water at T = 440 K and P = 8 GPa. Results are compared to a high pressure liquid and ice VII phases to improve the understanding of the plastic crystal phases. Entropy results indicate that the fcc crystal is more stable compared to the bcc structure under the studied conditions.
实验证实，水具有包含多种晶体的丰富相图。高压高温水对于地球地幔和系外行星研究具有重要意义。正是在水的相图这一区域，通过经典力场和从头算计算的计算机模拟揭示了水的新塑性晶体相。然而，这些塑性相在实验中仍然难以捉摸。在此，我们使用分子动力学和两相热力学方法对水的计算塑性晶体相的结构、动力学和热力学进行了全面表征，并揭示了它们之间的相互作用。在T = 440 K和P = 8 GPa条件下，获得了水的假设体心立方和面心立方塑性晶体相不同重取向相关函数的弛豫时间。将结果与高压液相和冰VII相进行比较，以增进对塑性晶体相的理解。熵的结果表明，在所研究的条件下，面心立方晶体相比体心立方结构更稳定。
