标题： 非平衡条件下体心立方铁的热诱导结构竞争力和亚稳定性 显示英文标题

标题： Thermal Induced Structural Competitiveness and Metastability of Body-centered Cubic Iron under Non-Equilibrium Conditions

摘要： 在高压物理以及地球与行星科学中，多兆巴压力下接近熔点的铁的结构和稳定性具有重要意义。虽然体心立方（BCC）相在较低温度下普遍被认为是不稳定的，但其在高温（约0.5 eV）下相对于六方密排（HCP）相在地球内核（IC）中的稳定性仍然是理论和实验争论的热点话题。 我们的从头计算表明，在较高的电子温度（>1-1.5 eV）下，势能面上的能量显著下降，出现了一个平台和局部最小值，并且所有声子模式都得到了稳定。这些效应增加了BCC、HCP和面心立方（FCC）相之间的竞争，并导致了BCC结构的亚稳态。 此外，BCC铁的热力学稳定性因其显著的晶格振动熵而增强。这种由热诱导的结构竞争力和非平衡条件下的亚稳态为理解铁相关系及固态化过程提供了清晰的理论框架，无论是实验上还是在地球内核中。 显示英文摘要

摘要： The structure and stability of iron near melting at multi-megabar pressures are of significant interest in high pressure physics and earth and planetary sciences. While the body-centered cubic (BCC) phase is generally recognized as unstable at lower temperatures, its stability relative to the hexagonal close-packed (HCP) phase at high temperatures (approximately 0.5 eV) in the Earth's inner core (IC) remains a topic of ongoing theoretical and experimental debate. Our ab initio calculations show a significant drop in energy, the emergence of a plateau and a local minimum in the potential energy surface, and stabilization of all phonon modes at elevated electron temperatures (>1-1.5 eV). These effects increase the competition among the BCC, HCP, and the face-centered cubic (FCC) phases and lead to the metastability of the BCC structure. Furthermore, the thermodynamic stability of BCC iron is enhanced by its substantial lattice vibration entropy. This thermally induced structural competitiveness and metastability under non-equilibrium conditions provide a clear theoretical framework for understanding iron phase relations and solidification processes, both experimentally and in the IC.