A reactive molecular dynamics model for uranium/hydrogen containing systems.

Area of Science:

• Materials Science
• Computational Chemistry
• Nuclear Engineering

Background:

• Uranium-based materials are critical in energy, medical, and military applications.
• Studying hydrogen embrittlement in uranium is difficult due to toxicity and high computational costs of quantum methods.

Purpose of the Study:

• To develop a computationally efficient method for simulating uranium-hydrogen interactions.
• To accurately model bulk structures, vacancies, and interstitial hydrogen in U and UH3.

Main Methods:

• Developed the Chebyshev Interaction Model for Efficient Simulation (ChIMES) potential.
• Validated ChIMES against Density Functional Theory (DFT) for structural parameters, formation energies, and diffusion barriers.
• Employed ChIMES for molecular dynamics simulations of hydrogen interstitial diffusion.

Main Results:

• ChIMES achieves DFT-like accuracy for U and UH3 systems.
• The model demonstrates linear scaling and significant computational efficiency improvements.
• ChIMES accurately predicts bulk structural parameters, vacancy formation energies, and diffusion barriers.
• Molecular dynamics simulations determined the diffusion activation energy for hydrogen interstitials.

Conclusions:

• ChIMES provides a computationally efficient and accurate approach for studying uranium-hydrogen interactions.
• The model is significant for simulating actinides and high-Z materials, bridging scales between experiments and quantum theory.