Time-resolved photoabsorption in finite systems : A first-principles NEGF approach
Perfetto, E., Uimonen, A.-M., van Leeuwen, R., & Stefanucci, G. (2016). Time-resolved photoabsorption in finite systems : A first-principles NEGF approach. In Progress in Non-equilibrium Green’s Functions (PNGF VI) (pp. 012004). Journal of Physics: Conference Series, 696. Institute of Physics Publishing Ltd.. doi:10.1088/1742-6596/696/1/012004
Published inJournal of Physics: Conference Series;696
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We describe a first-principles NonEquilibrium Green’s Function (NEGF) approach to time-resolved photoabsortion spectroscopy in atomic and nanoscale systems. The method is used to highlight a recently discovered dynamical correlation effect in the spectrum of a Krypton gas subject to a strong ionizing pump pulse. We propose a minimal model that captures the effect, and study the performance of time-local approximations versus time-nonlocal ones. In particular we implement the time-local Hartree-Fock and Markovian second Born (2B) approximation as well as the exact adiabatic approximation within the Time-Dependent Density Functional Theory framework. For the time-nonlocal approximation we instead use the 2B one. We provide enough convincing evidence for the fact that a proper description of the spectrum of an evolving admixture of ionizing atoms requires the simultaneous occurrence of correlation and memory effects.