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arXiv 1503.05417cond-mat.mtrl-sciphysics.chem-ph
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简单金属在暖密物质区的双温对势和声子谱

Two-temperature pair potentials and phonon spectra for simple metals in the warm dense matter regime

Louis Harbour, M. W. Chandre Dharma-wardana, Dennis D. Klug, Laurent J. Lewis

摘要:

我们开发的离子离子对电位的Al,Na和K的密度和温度相关的暖致密物质(WDM)制度。此外,我们强调离子温度$T_i$不同于电子温度$T_e$的非平衡态.这项工作主要集中在超快激光-金属相互作用,激光的能量几乎完全转移到电子子系统在飞秒时间尺度。这导致具有$T_e>T_i$和离子仍处于初始室温$T_i=T_r$的双温度系统。第一性原理计算,如密度泛函理论(DFT)或量子蒙特卡罗,由于缺乏有限的$T$功能,如赝势,和广泛的CPU时间要求,尚未完全可行的WDM条件。需要更简单的方法来研究这些高度复杂的系统。我们建议使用两个温度对势$U_{ii}(r, T_i,T_e)$从线性响应理论使用非线性电子密度$n(\mathbf{r})$从有限的$T$ DFT与一个单离子浸没在适当的电子流体。我们计算了$T_r$的平衡声子谱,发现与实验符合得很好。这为我们的非平衡声子色散关系提供了可信度,这些关系对于确定热物理性质、稳定性、能量弛豫机制和输运系数非常重要。

英文摘要:

We develop ion-ion pair potentials for Al, Na and K for densities and temperatures relevant to the warm-dense-matter (WDM) regime. Furthermore, we emphasize non-equilibrium states where the ion temperature $T_i$ differs from the electron temperature $T_e$. This work focuses mainly on ultra-fast laser-metal interactions where the energy of the laser is almost exclusively transferred to the electron sub-system over femtosecond time scales. This results in a two-temperature system with $T_e>T_i$ and with the ions still at the initial room temperature $T_i=T_r$. First-principles calculations, such as density functional theory (DFT) or quantum Monte Carlo, are as yet not fully feasible for WDM conditions due to lack of finite-$T$ features, e.g. pseudopotentials, and extensive CPU time requirements. Simpler methods are needed to study these highly complex systems. We propose to use two-temperature pair potentials $U_{ii}(r, T_i,T_e)$ constructed from linear-response theory using the non-linear electron density $n(\mathbf{r})$ obtained from finite-$T$ DFT with a single ion immersed in the appropriate electron fluid. We compute equilibrium phonon spectra at $T_r$ which are found to be in very good agreement with experiments. This gives credibility to our non-equilibrium phonon dispersion relations which are important in determining thermophysical properties, stability, energy-relaxation mechanisms and transport coefficients.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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