Ab-initio simulation of liquid water without artificial high temperature

Comprehending the structure and dynamics of water is crucial in various fields such as water desalination, ion separation, electrocatalysis, and biochemical processes. While reported works show that the ab-initio molecular dynamics (AIMD) can accu- rately portray water’s structure, the artificial high temperature (AHT) from 120K to 30K is needed to mimic the quantum nature of hydrogen-bond network from GGA, metaGGA to hybrid functionals. The AHT proves to be an inadequate approach for systems involving aqueous multiphase mixtures, such as water-solid interfaces and aque- ous solutions. This is due to the activation of additional phonons in other phases, which can lead to an overestimation of the dynamics for nearby water molecules. In this work, we find the regularized SCAN (rSCAN) functional can well capture both the structure and dynamics of liquid water at ambient conditions without AHT. Moreover, rSCAN can well match the experimental results of hydration structures for alkali, alkali earth and halide ions. We anticipate that the versatile and accurate rSCAN functional will emerge as a key tool based on ab-initio simulation for investigating chemical processes in aqueous environments.

理解水的结构和动力学对于水脱盐、离子分离、电催化和生物化学过程等众多领域至关重要。尽管已有研究指出，从头算分子动力学（AIMD）能够精确描绘水的结构，但为了模拟广义梯度近似（GGA）、元广义梯度近似（metaGGA）至混合泛函中氢键网络的量子特性，仍需采用从120K至30K的人为高温（AHT）。然而，对于涉及水-固界面和溶液等水多相混合系统的情形，AHT已被证明是一种不充分的方法。这是因为其他相中额外声子的激活可能导致对附近水分子的动力学估计过高。在本研究中，我们发现正则化扫描（rSCAN）泛函能够在无需AHT的条件下，很好地捕捉常温下液态水的结构和动力学。此外，rSCAN泛函能够很好地匹配碱金属、碱土金属和卤化物离子的水合结构实验结果。我们预期，这种多才多艺且精确的rSCAN泛函将成为基于从头算模拟研究水环境中化学过程的关键工具。