Berlin 2018 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 50: HL Poster IV
HL 50.15: Poster
Thursday, March 15, 2018, 19:00–21:00, Poster B
Effect of Exchange-correlation functional on spin-admixture parameter calculated from first principles — •Uday Chopra1,2, Shambhawi Pandey2,3, Sergei Egorov4, Jairo Sinova1, and Erik R. McNellis1 — 1Institute for Physics, Johannes Gutenberg University, Mainz, Germany — 2Graduate School Materials Science in Mainz, Germany — 3Department of Chemical Engineering, Indian Institute of Technology Roorkee, India — 4Department of Chemistry, University of Virginia, USA
Organic semiconductors (OSC) are known to have a small spin-orbit coupling (SOC) and this has strong implications in their spintronic properties. It has been shown that SOC can be characterised by mixing of up- and down-spin states and is expressed by the spin-admixture parameter, γ2[1]. This parameter governs the probability of a spin-flipping as the polaron hops between different sites in the OSC. Since for most OSC, transport is described by hopping mechanism, the spin-relaxation time is very sensitive to γ2 therefore it becomes important to determine the parameter with high accuracy. We present a method for calculation of spin-admixture in organic semiconductors from first-principles on the level of Density Functional Theory. In this work, we use a methodical procedure to obtain precise values of γ2 and demonstrate the effect of exchange-correlation functional on the parameter. Moreover, we generalise this approach under the Unrestricted DFT. We also find that γ2, strongly depends on the delocalization error of the functional and tends to decrease as the functional becomes more localized. [1] Z. G. Yu, Phys. Rev. B. 85, 115201, 2012.