First-principle calculation for electron excitation process dependence on high-harmonic generation

Otobe, Tomohito; Yabana, Kazuhiro*

We present the first-principles description for the non-linear excitation in dielectrics induced by an optical field and would like to present the new approach to probe electron excitation process. We rely upon the time-dependent density-functional theory with the adiabatic local-density approximation, and a real-space and real-time method is employed to solve the time-dependent Kohn-Sham equation. We distinguish the high harmonic generation by electron-hole recombination by Fourier transformation of electronic current after laser filed ends. We find the spectrum of this electric field presents the detail of the electron excitation process, multi-photon absorption and tunnel effect.