Data of the figures and machine learning potentials for "A molecular dynamics study on local structural features and thermophysical properties of the NaCl-UCl3 molten salt with machine learning potential"

NaCl-UCl3 molten salt is a potential fuel for the molten salt reactor due to its ability to dissolve higher actinides and excellent thermophysical properties. The composition of the NaCl-UCl3 salt changes due to the burn-up during the operation of the reactor, which makes it important to study the local structural features and determine the thermophysical properties for the entire composition space.Among the existing molecular dynamics (MD) methods, ab initio molecular dynamics (AIMD) simulations provide the highest accuracy. However, the AIMD calculations are computationally expensive and not feasible to calculate dynamic properties such as viscosity and thermal conductivity. In this work, using atomic cluster expansion (ACE), we developed the first transferable machine learning interatomic potential (MLIP) trained with density functional theory (DFT) data that covers the entire compositional space of the binary NaCl-UCl3 melt, and calculates the thermophysical properties of the binary melt with an accuracy of ab initio level and at a low computational cost equivalent to empirical interatomic potentials.The calculated useful thermophysical properties for the nuclear applications, such as density, excess molar volume, heat capacity, viscosity, and thermal conductivity will enrich the database of salt properties. In addition, a comprehensive analysis of the local structural features correlating the changes in the thermophysical properties will enhance the understanding of salt chemistry.NaCl-UCl₃熔盐因可溶解高价锕系元素且具备优异的热物理性质，是熔盐堆的潜在燃料。反应堆运行过程中，NaCl-UCl₃熔盐的组分会因燃耗发生改变，因此研究其局域结构特征并确定全组分空间内的热物理性质具有重要意义。在现有分子动力学（MD）方法中，从头算分子动力学（AIMD）模拟的精度最高，但该类计算的计算成本高昂，无法用于计算黏度、热导率等动态物性。本工作采用原子团簇展开（ACE）方法，开发了首个基于密度泛函理论（DFT）数据训练的可迁移机器学习原子间势（MLIP），其覆盖了二元NaCl-UCl₃熔盐的全组分空间，能够以接近从头算的精度、且等效于经验原子间势的低计算成本，预测该二元熔盐的热物理性质。本次计算得到的核应用所需的关键热物理性质，包括密度、超额摩尔体积、热容、黏度及热导率，将丰富熔盐性质数据库。此外，对与热物理性质变化相关的局域结构特征开展全面分析，将有助于加深对熔盐化学的理解。