Photoinduced dynamics of organic molecules using nonequilibrium Green's functions with second-Born, GW, T-matrix, and three-particle correlations

The ultrafast hole dynamics triggered by the photoexcitation of molecular targets is a highly correlated process even for those systems, such as organic molecules, having a weakly correlated ground state. We provide a unifying framework and a numerically efficient matrix formulation of state-of-the-art nonequilibrium Green's function (NEGF) methods such as second-Born as well as GW and T-matrix without and with exchange diagrams. Numerical simulations are presented for a paradigmatic, exactly solvable molecular system, and the shortcomings of the established NEGF methods are highlighted. We then develop a NEGF scheme based on the Faddeev treatment of three-particle correlations; the exceptional improvement over established methods is explained and demonstrated. The Faddeev NEGF scheme scales linearly with the maximum propagation time, thereby opening up prospects for femtosecond simulations of large molecules.