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State-of-the art ab initio calculations of electronic states and thermoelectric properties

Authors: S. Botti

Ref.: Annual Meeting of the GDR Thermoelectricity, Lyon, France, 06/12/2012 (2012)

Abstract: Research in thermoelectricity aims at finding novel thermoelectric materials that would allow for both decreasing the cost of the device and improving the energy conversion efficiency. In this context a strong collaboration between theory and experiment is crucial, as computers allow to screen thousands of compounds at a fraction of the time and the cost required by standard laboratory screening. In order to evaluate the quality of a thermoelectric material using a computer, one needs to calculate the figure of merit zT, which provides the maximum efficiency for both power generation and cooling. This key quantity depends on the Seebeck coefficient, the electrical conductivity and the thermal conductivity. I will focus here on the problem of determining accurately the electronic contributions. Electronic transport properties require the knowledge of electronic band structures. These can be routinely obtained from density functional theory using standard semi-local functionals. However, it is well known that this approach underestimates dramatically the band gap of semiconductors, with strong consequences on the transport properties. Nowadays it is possible to obtain accurate band structures using methods based on density functional theory that go beyond standard approximations. In this presentation I will review them and discuss the implications for thermoelectricity.