论文标题
迈向电子和材料中原子振动的超快动力学的精确模拟
Toward precise simulations of the coupled ultrafast dynamics of electrons and atomic vibrations in materials
论文作者
论文摘要
超快速光谱可以在短时间内访问电子和核的动力学，从而散发出材料中非平衡现象的灯光。但是，由于广泛采用的仿真方案仅限于次秒时间尺度或采用缺乏定量准确性的简化相互作用，因此可以开发准确的计算来解释这些实验。在这里，我们展示了一种精确的方法，以获得无等值电子和原子振动（声子）的时间相关种群，直到数十秒钟，并以飞秒时间的分辨率分辨率。将第一原理电子 - 音波和声子 - 音相互作用与平行的数值方案相结合，以时间步长时间耦合电子和声子玻尔兹曼方程，我们的方法提供了前所未有的微观显微镜洞察力，可洞悉激发材料中的散射机制。以石墨烯为例作为案例研究，我们演示了超快电子和声子动力学，瞬态光吸收，结构快照和弥漫性X射线散射的计算。我们的第一原理方法为材料中超快动态的定量原子模拟铺平了道路。
Ultrafast spectroscopies can access the dynamics of electrons and nuclei at short timescales, shedding light on nonequilibrium phenomena in materials. However, development of accurate calculations to interpret these experiments has lagged behind as widely adopted simulation schemes are limited to sub-picosecond timescales or employ simplified interactions lacking quantitative accuracy. Here we show a precise approach to obtain the time-dependent populations of nonequilibrium electrons and atomic vibrations (phonons) up to tens of picoseconds, with a femtosecond time resolution. Combining first-principles electron-phonon and phonon-phonon interactions with a parallel numerical scheme to time-step the coupled electron and phonon Boltzmann equations, our method provides unprecedented microscopic insight into scattering mechanisms in excited materials. Focusing on graphene as a case study, we demonstrate calculations of ultrafast electron and phonon dynamics, transient optical absorption, structural snapshots and diffuse X-ray scattering. Our first-principles approach paves the way for quantitative atomistic simulations of ultrafast dynamics in materials.
