Using first-principles molecular dynamics, we calculated the equation of state and shock Hugoniot of various boron phases. We find a large mismatch between Hugoniots based on existing knowledge of the equilibrium phase diagram and those measured by shock experiments, which could be reconciled if the $\alpha$-B$_{12}$/$\beta \rightarrow\gamma$-B$_{28}$ transition is significantly over-pressurized in boron under shock compression. Our results also indicate that there exists an anomaly and negative Clapeyron slope along the melting curve of boron at 100 GPa and 1500--3000 Kelvin. These results enable in-depth understanding of matter under shock compression, in particular the significance of compression-rate dependence of phase transitions and kinetic effects in experimental measurements.

中文翻译：

---

硼在冲击压缩下的相变

使用第一性原理分子动力学，我们计算了各种硼相的状态方程和激波 Hugoniot。我们发现基于平衡相图的现有知识和冲击实验测量的 Hugoniots 之间存在很大的不匹配，如果 $\alpha$-B$_{12}$/$\beta\rightarrow\gamma$ -B$_{28}$ 转变在冲击压缩下硼中显着过压。我们的结果还表明，沿着硼在 100 GPa 和 1500--3000 Kelvin 的熔化曲线存在异常和负 Clapeyron 斜率。这些结果有助于深入了解冲击压缩下的物质，特别是实验测量中相变和动力学效应的压缩率依赖性的重要性。