Milestone report on MD potential development for uranium silicide

Yu, Jianguo¹  Zhang, Yongfeng¹  Hales, Jason Dean¹ 

[1] Idaho National Lab. (INL), Idaho Falls, ID (United States). Fuel Modeling and Simulation Dept.

关键词: INTERATOMIC FORCES;    POTENTIALS;    URANIUM SILICIDES;    FORMATION HEAT;    LATTICE PARAMETERS;    DENSITY FUNCTIONAL METHOD;    TEMPERATURE RANGE 1000-4000 K;    TEMPERATURE RANGE 0400-10;   

DOI  :  10.2172/1262493
RP-ID  :  INL/EXT--16-38289
PID  :  OSTI ID: 1262493
Others  :  TRN: US1601608

美国|英语

来源: SciTech Connect

【 摘 要 】

This report summarizes the progress on the interatomic potential development of triuranium-disilicide (U₃Si₂) for molecular dynamics (MD) simulations. The development is based on the Tersoff type potentials for single element U and Si. The Si potential is taken from the literature and a Tersoff type U potential is developed in this project. With the primary focus on the U₃Si₂ phase, some other U-Si systems such as U₃Si are also included as a test of the transferability of the potentials for binary U-Si phases. Based on the potentials for unary U and Si, two sets of parameters for the binary U-Si system are developed using the Tersoff mixing rules and the cross-term fitting, respectively. The cross-term potential is found to give better results on the enthalpy of formation, lattice constants and elastic constants than those produced by the Tersoff mixing potential, with the reference data taken from either experiments or density functional theory (DFT) calculations. In particular, the results on the formation enthalpy and lattice constants for the U₃Si₂ phase and lattice constants for the high temperature U₃Si (h-U₃Si) phase generated by the cross-term potential agree well with experimental data. Reasonable agreements are also reached on the elastic constants of U₃Si₂, on the formation enthalpy for the low temperature U₃Si (m-U₃Si) and h-U₃Si phases, and on the lattice constants of m-U₃Si phase. All these phases are predicted to be mechanically stable. The unary U potential is tested for three metallic U phases (??, ??, ??). The potential is found capable to predict the cohesive energies well against experimental data for all three phases. It matches reasonably with previous experiments on the lattice constants and elastic constants of ??U.