Ab-initio density functional theory (DFT) has been successful for calculations of ground state properties of various materials. Time-dependent density functional theory (TDDFT) is an extension of the DFT and can describe electron dynamics in molecules, nano-structures, and solids induced by optical electric fields. We have been developing a computational method to describe electron dynamics in molecules and crystalline solids solving the time-dependent Kohn-Sham equation in real time [1]. In the first part of my seminar, I will talk on basic and historical aspects of the method and its applications. Applications of the real-time TDDFT are classified into two: One is for efficient calculations of linear optical responses. The other is for the description of extremely nonlinear electron dynamics induced by strong fields such as an intense and ultrashort laser pulse. In the second part of my seminar, I will talk on our recent applications of the real-time TDDFT to attosecond spectroscopies in crystalline solids. We have developed an ab-initio scheme coupling the real-time TDDFT with the macroscopic Maxwell equations in a multiscale implementation [2]. The method can describe propagations of ultrashort laser pulses in dielectrics and, in particular, the energy transfer from the pulsed light to electrons in dielectrics without any empirical parameters. We apply the method to analyze recent experiments employing attosecond spectroscopy methods [3,4].

References:
[1] K. Yabana, G.F. Bertsch, “Time-dependent local-density approximation in real time”, Phys. Rev. B54, 4484 (1996).
[2] K. Yabana, T. Sugiyama, Y. Shinohara, T. Otobe, G.F. Bertsch, “Time-dependent density functional theory for strong electromagnetic fields in crystalline solids”, Phys. Rev. B85, 045134 (2012).
[3] M. Lucchini et.al, “Attosecond dynamical Franz-Keldysh effect in polycrystalline diamond”, Science 353, 916 (2016).
[4] A. Sommers et.al, “Attosecond nonlinear polarization and light-matter energy transfer in solids”, Nature 534, 86 (2016).

Prof. Yabana received his M.S. in 1987 and PhD in 1987 from Kyoto University (Japan). After working as researcher at Michigan State University (USA) and University of Washington (USA), he joined the faculty at Niigata University (Japan). In 1999, he moved to University of Tsukuba (Japan) and then promoted to full professor in 2002. His research interests focus on computational physics, theoretical condensed matter physics and nuclear physics.