セミナー(2015.12.18)：Das Pemmaraju氏 (LBNL)
2015年12月15日 | 新着情報
Dec.18, 2015, 13:45 at D312 (自然学系D棟)
Speaker: Das Pemmaraju (The Molecular Foundry and Chemical Sciences
Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA)
Title: First-principles interpretation of attosecond time-resolved XUV absorption spectroscopy of laser excited Silicon
Abstract: The availability of ultrafast x-ray pulses both from powerfulfree electron laser light-sources as well as table top high-harmonicgeneration, has significantly enhanced the utility of core-levelspectroscopies as probes for investigating dynamical processes infunctional materials. Theoretical approaches to complement these time-domain experiments are therefore actively being developed. In this context, I will discuss recent efforts that employ a combination of real-time time-dependent density functional theory (TDDFT), occupancy-constrained density functional theory and many-body perturbation theory approaches to help interpret spectral signatures in attosecond time-resolved core-level spectroscopic measurements on laser-excited silicon. Out-of-equilibrium electron-hole densities obtained from real-time TDDFT simulations of the valence electron dynamics are used to estimate the transient modulation of L-edge absorption in femtosecond infrared pump – attosecond XUV probe experiments. Furthermore, the contribution of electron-phonon and electron-electron scattering mechanisms to the lifetime broadening observed in measured L-edge spectra is estimated using occupation-constrained density functional theory and GW calculations respectively.