Time-resolved photoabsorption in finite systems: A first-principles NEGF approach

Progress in Non-equilibrium Green's Functions

Perfetto, E.^1 ; Uimonen, A.-M.^2,3 ; Van Leeuwen, R.^2,4 ; Stefanucci, G.^1,4,5

Dipartimento di Fisica, Università di Roma Tor Vergata, Via della Ricerca Scientifica 1, Rome

I-00133, Italy^1

Department of Physics, Nanoscience Center, University of Jyväskylä, Jyväskylä

FIN 40014, Finland^2

Clarendon Laboratory, University of Oxford, Parks Road, Oxford

OX1 3PU, United Kingdom^3

European Theoretical Spectroscopy Facility (ETSF), Finland^4

Laboratori Nazionali di Frascati, Istituto Nazionale di Fisica Nucleare, Via E. Fermi 40, Frascati

00044, Italy^5

关键词: Adiabatic approximations;    Dynamical correlations;    First principles;    Local approximation;    Nano-scale system;    Non-equilibrium Green's function;    Photoabsorptions;    Time dependent density functional theory;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/696/1/012004/pdf
DOI  :  10.1088/1742-6596/696/1/012004

来源: IOP

【 摘 要 】

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.