*Article* **Atomic Simulations of U-Mo under Irradiation: A New Angular Dependent Potential**

**Wenhong Ouyang, Wensheng Lai, Jiahao Li, Jianbo Liu \* and Baixin Liu**

The Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China; oywh18@mails.tsinghua.edu.cn (W.O.); wslai@mail.tsinghua.edu.cn (W.L.); lijiahao@mail.tsinghua.edu.cn (J.L.); dmslbx@mail.tsinghua.edu.cn (B.L.) **\*** Correspondence: jbliu@mail.tsinghua.edu.cn

**Abstract:** Uranium-Molybdenum alloy has been a promising option in the production of metallic nuclear fuels, where the introduction of Molybdenum enhances mechanical properties, corrosion resistance, and dimensional stability of fuel components. Meanwhile, few potential options for molecular dynamics simulations of U and its alloys have been reported due to the difficulty in the description of the directional effects within atomic interactions, mainly induced by itinerant f-electron behaviors. In the present study, a new angular dependent potential formalism proposed by the author's group has been further applied to the description of the U-Mo systems, which has achieved a moderately well reproduction of macroscopic properties such as lattice constants and elastic constants of reference phases. Moreover, the potential has been further improved to more accurately describe the threshold displacement energy surface at intermediate and short atomic distances. Simulations of primary radiation damage in solid solutions of the U-Mo system have also been carried out and an uplift in the residual defect population has been observed when the Mo content decreases to around 5 wt.%, which corroborates the negative role of local Mo depletion in mitigation of irradiation damage and consequent swelling behavior.

**Keywords:** uranium; molybdenum; molecular dynamics; interatomic potential
