发表机构
The Hong Kong University of Science and Technology（香港科技大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过AIMD模拟比较不同泛函在极端条件下超临界水的性质，发现vdW影响减弱而O-H键强度影响质子转移，为地幔水研究提供指导。
AI 中文摘要
高压高温（HP-HT）下水的性质对地球深部的多种地球化学过程至关重要。从头算分子动力学（AIMD）是一种无需经验参数即可研究极端条件下水的有前景的方法。然而，AIMD模拟的准确性取决于密度泛函理论计算中使用的交换关联（XC）泛函（包括色散校正）。虽然范德华（vdW）相互作用众所周知对常温条件下水的性质至关重要，但色散校正对地球地幔中发现的HP-HT水性质的影响在很大程度上尚未被探索。为解决这一问题，我们在1、5和10 GPa及1000 K条件下对超临界水进行了AIMD模拟。我们比较了PBE、PBE-D3、RPBE-D3和SCAN泛函，其中D3表示Grimme的D3色散校正。我们比较了使用这些XC泛函计算的水的结构、扩散和振动性质。总体而言，在极端P-T条件下，各泛函之间的差异相对于常温条件有所减小。PBE和PBE-D3表现出比RPBE-D3和SCAN更高的质子转移速率，这表明虽然vdW相互作用在极端条件下对水结构影响不显著，但氧-氢键强度确实影响质子转移。我们的结果为地幔中的水提供了分子层面的见解，并为在极端条件下水溶液的AIMD模拟中选择合适的XC泛函提供了宝贵指导。
英文摘要
The properties of water under high pressure and high temperature (HP-HT) are critical in multiple geochemical processes in deep Earth. Ab initio molecular dynamics (AIMD) is a promising approach to study water under extreme conditions without any empirical parameters. However, the accuracy of AIMD simulations is determined by the exchange-correlation (XC) functional including the dispersion correction used in density functional theory calculations. While van der Waals (vdW) interactions are well known to be critically important for water under ambient conditions, the influence of the dispersion correction on the properties of HP-HT water as found in Earth's mantle remains largely unexplored. To address this, we carried out AIMD simulations for supercritical water at 1, 5, and 10 GPa, and 1000 K. We compared PBE, PBE-D3, RPBE-D3, and SCAN functionals, where D3 means Grimme's D3 dispersion correction. We compared the structural, diffusion, and vibrational properties of water as computed with these XC functionals. Overall, the discrepancies between the functionals are reduced under extreme P-T conditions relative to ambient conditions. PBE and PBE-D3 exhibit higher proton-transfer rates than RPBE-D3 and SCAN, suggesting that while vdW interactions do not significantly affect the water structure under extreme conditions, the oxygen-hydrogen bond strength does influence proton transfer. Our results provide molecular-level insight into water in Earth's mantle and offer valuable guidance for selecting appropriate XC functionals in AIMD simulations of aqueous solutions under extreme conditions.
