标题： 与超短光脉冲相互作用的薄材料的时间依赖密度泛函理论 显示英文标题

标题： Time-dependent density functional theory for interaction of ultrashort light pulse with thin materials

摘要： 我们提出了一种基于第一性原理时间依赖密度泛函理论的理论描述，用于超短光脉冲垂直照射薄材料的情况。 作为最详尽的方案，我们开发了一种微观描述方法，在时间域中同时求解光电磁场的麦克斯韦方程和电子动力学的时间依赖Kohn-Sham方程，使用共同的空间网格。 我们称之为微观麦克斯韦-TDDFT方案。 我们对该方案进行了测试，针对不同厚度的硅薄膜，从几个原子层到几纳米。 我们表明，微观麦克斯韦-TDDFT方案能够提供令人满意的描述，在第一性原理水平上包含薄膜的电子结构、电磁场在表面的多次反射以及当入射光脉冲较强时的非线性光-物质相互作用。 然而，随着厚度的增加，计算变得昂贵。 随后，我们考虑了两种极限情况：极薄和足够厚的薄膜，并开发了近似方案。 对于极薄的情况，包括二维原子层材料，发展了一种二维宏观电磁学：对于弱场引入二维极化率，而对于强场推导出时间演化方程。 对于足够厚的薄膜，微观麦克斯韦-TDDFT方案预计会与利用普通宏观电磁学的描述一致。 我们通过数值比较计算结果来确认这一点：对于弱场，与使用体电介质极化率的描述进行比较。 对于强场，与作者小组之前开发的多尺度麦克斯韦-TDDFT方案进行比较。 显示英文摘要

摘要： We present a comprehensive theoretical description for an irradiation of an ultrashort light pulse normally on thin materials based on first-principles time-dependent density functional theory. As the most elaborate scheme, we develop a microscopic description solving Maxwell equations for light electromagnetic fields and the time-dependent Kohn-Sham equation for electron dynamics simultaneously in the time domain using a common spatial grid. We call it the microscopic Maxwell-TDDFT scheme. We test this scheme for silicon thin films of various thickness, from a few atomic layers to a few tens of nm. We show that the microscopic Maxwell-TDDFT scheme provides a satisfactory description incorporating the electronic structure of thin films in the first-principles level, multiple reflections of the electromagnetic fields at the surfaces, and nonlinear light-matter interaction when the incident light pulse is strong. However, the calculation becomes expensive as the thickness increases. We then consider two limiting cases of extremely thin and sufficiently thick films and develop approximate schemes. For the extremely thin case including two-dimensional atomic-layered materials, a two-dimensional macroscopic electromagnetism is developed: a two-dimensional susceptibility is introduced for a weak field, while time evolution equation is derived for an intense field. For sufficiently thick films, the microscopic Maxwell-TDDFT scheme is expected to coincide with a description utilizing ordinary macroscopic electromagnetism. We numerically confirm it comparing the calculated results: For a weak field, a comparison is made with a description using the bulk dielectric susceptibility. For a strong field, a comparison is made with a multiscale Maxwell-TDDFT scheme which the authors' group developed previously.