论文标题
多$ K $ - 定期系统的非绝热分子动力学
A multi $k$-point nonadiabatic molecular dynamics for periodic systems
论文作者
论文摘要
随着用于固态系统中载体动力学的超快速实验技术的快速开发，对相关现象（尤其是第一原则计算）的微观理解非常需要。非绝热分子动力学（NAMD）提供了载体转移或载体热化的实时直接模拟。但是，当应用于分子动力学期间$γ$ - 点声子运动时，应用于定期超级电池时，在NAMD模拟过程中没有超级电池电子$ k $ - 点交叉。这通常会导致由于单个超级电池$ k $ - 点频段结构的明显能量差距而引起的过渡速率的大幅低估。在这项工作中，基于用于NAMD的表面跳跃方案，我们提出了一种实用方法，以实现定期系统的交叉$ K $过渡。我们通过证明了小型超级电池中的多$ k $ point NAMD的热电子热化过程来证明我们的形式主义，相当于在一个大型超级电池中使用单个$γ$ $ $ k $ - 点的模拟。还进行了散装硅的热载体热化过程，并将其与最近的超快速实验进行了比较。
With the rapid development of ultra-fast experimental techniques used for carrier dynamics in solid-state systems, a microscopic understanding of the related phenomena, particularly a first-principle calculation is highly desirable. Non-adiabatic molecular dynamics (NAMD) offers a real-time direct simulation of the carrier transfer or carrier thermalization. However, when applied to a periodic supercell, due to the $Γ$-point phonon movement during the molecular dynamics, there is no supercell electronic $k$-point crossing during the NAMD simulation. This often leads to a significant underestimation of the transition rate due to significant energy gaps in the single supercell $k$-point band structure. In this work, based on the surface hopping scheme used for NAMD, we propose a practical method to enable the cross-$k$ transition for a periodic system. We demonstrate our formalism by showing that the hot electron thermalization process by the multi $k$-point NAMD in a small supercell is equivalent to such simulation in a large supercell with single $Γ$ $k$-point. The hot carrier thermalization process in the bulk silicon is also carried out and compared with the recent ultra-fast experiments with excellent agreements.
