Watson William A, Cooper Sophie, Horton Matthew, Grimes Robin W
Department of Materials, Imperial College London, London, SW7 2AZ, UK.
United Kingdom National Nuclear Laboratory Limited, Chadwick House, Birchwood Park, Warrington, WA3 6AE, UK.
Sci Rep. 2025 Jun 6;15(1):19873. doi: 10.1038/s41598-025-03910-y.
Atomic scale computer simulations based on density functional theory (DFT) are used to calculate the formation energies and structures associated with phases in the U-N, Pu-N, U-C and Pu-C systems. Stable phases across the compositional spaces, from the metal to the nitrogen gas or graphite end members, are identified using convex hull analysis. Many predicted phases correspond to those known from experimental phase diagrams (e.g. UN, UN; PuN; UC, UC; PuC). However, many phases only sit on the convex hull upon inclusion of a suitably characterised Hubbard parameter (i.e. DFT + U). A nonstoichiometric composition of UN is identified on the U-N convex hull but others, including stoichiometric UN, are close to the line. A stoichiometric structure for PuC with [Formula: see text] symmetry is identified, alongside which a nonstoichiometric PuC phase has a similar energy.
基于密度泛函理论（DFT）的原子尺度计算机模拟被用于计算U-N、Pu-N、U-C和Pu-C体系中与各相相关的形成能和结构。使用凸包分析来确定整个成分空间中从金属到氮气或石墨端元的稳定相。许多预测的相与实验相图中已知的相相对应（例如UN、UN；PuN；UC、UC；PuC）。然而，许多相只有在包含适当表征的哈伯德参数（即DFT+U）时才位于凸包上。在U-N凸包上确定了一种非化学计量组成的UN，但其他相，包括化学计量的UN，都接近这条线。确定了具有[公式：见正文]对称性的PuC的化学计量结构，与之相比，一种非化学计量的PuC相具有相似的能量。
