Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 117: Organic semiconductors: Material properties (with CPP/DS)

HL 117.1: Vortrag

Freitag, 4. April 2014, 10:30–10:45, POT 051

Pressure dependent Electronic Structure from First Principles — •Franz Knuth1, Christian Carbogno1, Volker Blum1,2, and Matthias Scheffler11Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany — 2MEMS Department, Duke University, Durham, NC, USA

The electronic properties of organic semiconductors typically exhibit a significant dependence on the strain, stress and pressure [1]. To clarify the role of these effects electronic-structure theory is uniquely suited. However, standard density-functional theory approaches that neglect van-der-Waals interactions and that treat exchange and correlation in a semi-local approximation often fail to describe organic materials properly. To overcome this limitation, we have extended our implementation of the analytical strain derivatives (stress tensor) to include the contributions that stem from (a) the van-der-Waals interaction [2] and (b) the Fock-exchange in hybrid functionals. We discuss the details of our implementation that is based on a local resolution of identity (LVL) of the Coulomb matrix [3]. We validate our approach by investigating the geometric and electronic changes that occur in polyacetylene, polyaniline, and anthracene under pressure. We show that the fraction of exact exchange included in the calculations is critical – and non-trivial to choose – for a correct description of these systems.

[1] J. H. Kim, S. Seo, and H. H. Lee, Appl. Phys. Lett. 90, 143521 (2007).

[2] A. Tkatchenko, and M. Scheffler, PRL 102, 073005 (2009)

[3] A. Sodt, and M. Head-Gordon, J. Chem. Phys. 128, 104106 (2008)

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