Regensburg 2013 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 28: Transport & Diffusion III

MM 28.3: Talk

Tuesday, March 12, 2013, 15:30–15:45, H26

Thermoelectric Transport Coefficients from First Principles — •Karsten Rasim, Christian Carbogno, and Matthias Scheffler — Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, Berlin, Germany

Significant effort is currently being invested in the search and optimization of thermoelectric (TE) materials, which promise ecologic and economic impact for waste-heat recovery [1]. Respective first-principles studies of the TE transport coefficients have almost exclusively relied on the Boltzmann-transport framework; the electron-phonon coupling is thereby accounted for within first-order perturbation theory [2]. However, such approaches become increasingly questionable at high temperatures due to anharmonic effects and do not allow the assessment of the Seebeck coefficient. The Greenwood-Kubo (GK) method, which includes those effects via ab initio molecular dynamics, does not suffer these limitations and provides access to all electronic transport coefficients even at high temperatures. In fact, it has hitherto been used for matter under extreme thermodynamic conditions, e.g, for melts and plasmas [3], but not for condensed materials. We demonstrate and analyze the applicability of the GK method for TE compounds, discuss the required adaptations, the accuracy and the limits of this approach by computing the transport coefficients for direct/indirect band gap semiconductors.

[1] G. J. Snyder and E. S. Toberer, Nature Mat. 7, 105-114 (2008)

[2] P. Boulet and M. J. Verstraete, Comp. Mat.Sci. 50, 3 (2001)

[3] V. Recoules and J.-P. Crocombette, Phys. Rev. B 72, 104202 (2005).