论文标题
液体SI在高压下方熔融线的高压下的结构和动态特征
Structural and dynamic features of liquid Si under high pressure above the melting line minimum
论文作者
论文摘要
我们报告了一个{\ it hib ix}仿真研究，沿等温线1150〜K沿7个压力，液体Si的结构和动态特性变化，范围从10.2 GPa到24.3 GPa，这是熔化线的最小值以上的。压力从10.2 GPA增加到16 GPA会导致最亲密的邻居的四面体订购量强劲降低。扩散系数显示了原子体积的线性衰减与下降，这与简单液体金属的理论预测一致，因此在与不同晶相边界相对应的压力下未显示任何特征。速度自相关函数的傅立叶光谱在压力20及更高的压力下显示了两峰结构。这些特征频率与第二个伪 - 奶油区域中横向电流光谱函数的峰值频率很好。对于所有研究的压力，观察到两个短波长横向模式的几乎平坦的分支。我们讨论集体模式的纵向和横向分支中特征频率的压力演化。
We report an {\it ab initio} simulation study of changes in structural and dynamic properties of liquid Si at 7 pressures ranging from 10.2 GPa to 24.3 GPa along the isothermal line 1150~K, which is above the minimum of the melting line. The increase of pressure from 10.2 GPa to 16 GPa causes strong reduction in the tetrahedral ordering of the most close neighbors. The diffusion coefficient shows a linear decay vs drop in atomic volume, that agrees with theoretical prediction for simple liquid metals, thus not showing any feature at the pressures corresponding to the different crystal phase boundaries. The Fourier-spectra of velocity autocorrelation function shows two-peak structure at pressures 20 GPa and higher. These characteristic frequencies correspond well to the peak frequencies of the transverse current spectral function in the second pseudo-Brillouin zone. Two almost flat branches of short-wavelength transverse modes were observed for all the studied pressures. We discuss the pressure evolution of characteristic frequencies in the longitudinal and transverse branches of collective modes.
