Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 20: Poster Monday: Electronic Structure

O 20.10: Poster

Montag, 1. April 2019, 17:45–20:00, Poster F

Calculation of non-equilibrium occupation function — •Jonas Fey, Jonas F. Schäfer, Alexander Fabian, Philipp Risius, Michael Czerner, and Christian Heiliger — Institut für theoretische Physik, Justus-Liebig-Universität Gießen, Heinrich-Buff-Ring 16, 35392 Gießen

The development of new nanoscale devices requires a precise theoretical description. This can be realized within the Keldysh formalism by means of non-equilibrium Green’s functions. In order to increase the accuracy or number of these calcuations the numerical effort should be kept as low as possible. In the case that the occupation function of the system is known the numerical effort can be decreased by allowing the energy to take complex values and using the residue theorem to calculate an occuring integral along paths in the complex energy plane. This is for example the case for equilibrium systems. We were able to show that for a simple model system this trick can be extended to non-equilibrium. By applying the Keldysh formalism to complex valued energies one obtains an equation to calculate the occupation function. The effects of this method on the numerical effort were examined depending on the desired accuracy.