Faculty of Physics, University of Vienna, A-1090 Vienna, Austria.
Department of Lithospheric Research, University of Vienna, Josef-Holaubuek-Platz 2, 1090 Vienna, Austria.
J Chem Phys. 2023 May 28;158(20). doi: 10.1063/5.0151011.
Molecular simulations employing empirical force fields have provided valuable knowledge about the ice growth process in the past decade. The development of novel computational techniques allows us to study this process, which requires long simulations of relatively large systems, with ab initio accuracy. In this work, we use a neural-network potential for water trained on the revised Perdew-Burke-Ernzerhof functional to describe the kinetics of the ice-water interface. We study both ice melting and growth processes. Our results for the ice growth rate are in reasonable agreement with previous experiments and simulations. We find that the kinetics of ice melting presents a different behavior (monotonic) than that of ice growth (non-monotonic). In particular, a maximum ice growth rate of 6.5 Å/ns is found at 14 K of supercooling. The effect of the surface structure is explored by investigating the basal and primary and secondary prismatic facets. We use the Wilson-Frenkel relation to explain these results in terms of the mobility of molecules and the thermodynamic driving force. Moreover, we study the effect of pressure by complementing the standard isobar with simulations at a negative pressure (-1000 bar) and at a high pressure (2000 bar). We find that prismatic facets grow faster than the basal one and that pressure does not play an important role when the speed of the interface is considered as a function of the difference between the melting temperature and the actual one, i.e., to the degree of either supercooling or overheating.
在过去的十年中，采用经验力场的分子模拟为冰的生长过程提供了有价值的知识。新计算技术的发展使我们能够以从头算的精度研究这个需要对相对较大的系统进行长时间模拟的过程。在这项工作中，我们使用了经过修正的 Perdew-Burke-Ernzerhof 泛函训练的水的神经网络势来描述冰-水界面的动力学。我们研究了冰的融化和生长过程。我们得到的冰生长速率的结果与先前的实验和模拟结果相当吻合。我们发现冰融化的动力学呈现出与冰生长不同的行为（单调）。特别是，在 14 K 的过冷度下，发现冰的最大生长速率为 6.5 Å/ns。通过研究基面和初级和次级棱柱面，我们探讨了表面结构的影响。我们使用 Wilson-Frenkel 关系来解释这些结果，从分子的迁移率和热力学驱动力的角度来解释。此外，我们通过在负压力（-1000 巴）和高压力（2000 巴）下补充标准等压模拟来研究压力的影响。我们发现棱柱面比基面生长得更快，并且当将界面的速度作为熔化温度与实际温度之间的差异（即过冷或过热的程度）的函数来考虑时，压力并没有起到重要作用。
