Ni、Fe杂质在LBE中的化学行为的深度势能分子动力学研究  

Investigation on Chemical Behavior of Ni and Fe Impurities in LBE by Deep Potential Molecular Dynamics Simulation

作　　者：梁汝婷 薄涛 聂长明[1] 张蕾 柴之芳 石伟群[3] LIANG Ruting;BO Tao;NIE Changming;ZHANG Lei;CHAI Zhifang;SHI Weiqun(School of Chemistry and Chemical Engineering,University of South China,Hengyang 421001,China;Engineering Laboratory of Advanced Energy Materials,Ningbo Institute of Materials Technology and Engineering,Chinese Academy of Sciences,Ningbo 315201,China;Laboratory of Nuclear Energy Chemistry,Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]南华大学化学化工学院,湖南衡阳421001 [2]中国科学院宁波材料技术与工程研究所先进能源材料实验室,浙江宁波315201 [3]中国科学院高能物理研究所核能放射化学实验室,北京100049

出　　处：《原子能科学技术》2023年第12期2376-2387,共12页Atomic Energy Science and Technology

基　　金：国家自然科学基金(12105196)。

摘　　要：液态铅铋共晶(LBE)与结构材料的相容性,是其在先进反应堆中应用的难题之一。实验方法研究材料腐蚀产生的杂质原子在LBE中的扩散性质等化学行为较为困难,而传统的理论计算包括密度泛函理论(DFT)和经典分子动力学(MD)方法分别存在模拟尺度与模拟精度的限制。为了解决这一问题,本文采用近年提出的基于DFT计算、机器学习和深度神经网络的深度势能(DP)力场训练方法。该方法通过DFT计算生成数据集进行深度学习,得到能准确描述原子间作用力的DP模型。使用DP模型进行MD模拟,既能具有DFT的精度也能进行大体系和长时间尺度的模拟。本文研究了杂质原子Ni、Fe在LBE中的微观结构和扩散系数,同时计算了LBE的密度、热容、黏度等热物理性能参数。结果表明,杂质原子与Bi原子有更强的作用力,温度升高,原子间的作用力减小,两种杂质原子有着相似的配位情况,但Ni原子的配位数(CN)分布较为分散,Fe的CN较为集中,Ni相对于Fe在LBE中有更快的扩散速度。预测的密度、热容、黏度等热物理性能参数与实验结果吻合良好,并且优于经典力场MD的结果。The compatibility of liquid lead-bismuth eutectic(LBE)with structural materials is one of the problems in its application in advanced nuclear reactors.At present,the understanding of impurity atoms diffusion in liquid LBE is still limited.It is particularly difficult to study the chemical behaviors such as diffusion properties of impurity atoms in LBE by experimental methods.However,traditional theoretical calculations such as density functional theory(DFT)and classical molecular dynamics(MD)methods have dilemmas in simulation scale and simulation accuracy.To address those issues,a scheme based on DFT calculation,deep neural networks,and machine learning was introduced.By training on high-quality data sets generated by DFT calculations,three deep potential(DP)models of LBE,LBE-Ni,and LBE-Fe were constructed to describe the interaction between atoms.The results of AIMD calculation of radial distribution function(RDF)can be repeated by DPMD.By performing MD simulations with DP models,the microstructures of Ni,Fe impurities in LBE and the thermal physical properties of LBE were investigated.Meanwhile,the estimated thermophysical properties were discussed,including density,specific heat capacity,shear viscosity,and self-diffusion coefficient of Ni and Fe atoms.The higher RDF peaks of Bi-Ni and Bi-Fe reveal that both impurity atoms interact more strongly with Bi atoms.The predicted thermophysical properties are in good agreement with the experimental results,and have better accuracy than the results of the classical MD that based on the embedded atom method(EAM).In conclusion,a thorough understanding of the microstructure of impurities in LBE is provided and the data of the thermophysical properties of LBE are enriched.

关 键 词：LBE 热物理性质 扩散系数 第一性原理 分子动力学 机器学习 

分 类 号：TL99[核科学技术—核技术及应用] O572[理学—粒子物理与原子核物理]