Dresden 2017 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 55: Electronic-Structure Theory: New Concepts and Developments in Density Functional Theory and Beyond - IV
HL 55.5: Vortrag
Mittwoch, 22. März 2017, 11:45–12:00, GER 38
DFTB-based recursive Green’s function algorithms for electron transport in quasi-1D systems — •Fabian Teichert1,2,4, Andreas Zienert3,4, Jörg Schuster4, and Michael Schreiber2 — 1Dresden Center for Computational Materials Science (DCMS), Dresden, Germany — 2Institute of Physics, Technische Universität Chemnitz, Chemnitz, Germany — 3Center for Microtechnologies (ZfM), Technische Universität Chemnitz, Chemnitz, Germany — 4Fraunhofer Institute for Electronic Nano Systems (ENAS), Chemnitz, Germany
Within the last decades, quantum transport theory and density functional theory have become very important for predicting the electronic properties of new materials and future electronic devices.
We focus on the problem of improving quantum transport algorithms for large quasi-1D systems which are enormously time-consuming today. We combine the density functional tight binding (DFTB) approach with the recursive Green’s function formalism (RGF), which is very effective for such systems. First, we show how to improve the RGF for the case of randomly distributed real defects. For this, we use the steps of the renormalization decimation algorithm (RDA), which is part of the electrode calculation. Second, we show how to improve the calculation of the surface Green’s functions of electrodes which have a long unit cell. Here, we employ the decimation technique to reduce the dimensionality of the periodic Hamiltonian matrix, leading to effective matrices, which are treated by the RDA. Finally, we apply these algorithms to carbon nanotubes and present our results.