Density-Functional Theory of Thermoelectric Phenomena

• Applicant: Dr. Florian Eich
• Subject Area: Theoretical Condensed Matter Physics
• Term: from 2014 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 269251049

Thermoelectricity, the interplay of charge and heat, has gained momentum in recent years due to its potential impact on the development of sustainable energy sources. Any energy production process is accompanied by waste heat. Part of the energy is lost to the environment, for example in plumes from power plants. Thermoelectric devices, which efficiently convert heat flow to charge flow, could be used to convert part of the waste heat back to electrical energy enhancing the overall efficiency of energy production. With the advent of experimental techniques such as scanning thermal microscopy, charge and heat transfer processes can nowadays be studied at nanoscale resolution. This means that the search for efficient thermoelectric devices has entered length and time scales where the laws of quantum mechanics govern the dynamics of the system. On the theoretical side this opens conceptual riddles: How are we to define macroscopic concepts, such as temperature or heat flow at the nanoscale where the laws of quantum mechanics are applicable? Can we predict the thermoelectric properties of a device starting from the fundamental equations of quantum mechanics? This project is devoted to advancing a novel approach to address these and related questions on thermoelectric properties from first principles. We propose to generalize the well-established framework of time-dependent Density-Functional Theory to the realm of thermoelectric phenomena. As any density-functional approach, the proposed time-dependent thermal Density-Functional Theory requires physically sound approximations in order to allow an ab-initio computation of thermoelectric transport coefficients. We will focus on the construction of such approximations taking dynamical effects into account which are known to be a crucial feature in order to properly describe transport in a density-functional theory framework. To put our approach on a firm mathematical basis, we plan to investigate under which conditions a mapping theorem for our thermal Density-Functional Theory can be established.

• DFG Programme: Research Fellowships
• International Connection: USA
• Host: Professor Dr. Giovanni Vignale