Steady-state density functional theory for thermoelectric effects

Physical Review B 100, 195142 (2019)

Steady-state density functional theory for thermoelectric effects

Nahual Sobrino, Roberto D’Agosta, Stefan Kurth

The recently proposed density functional theory for steady-state transport (i-DFT) is extended to include temperature gradients between the leads. Within this framework, a general and exact expression is derived for the linear Seebeck coefficient which can be written as the sum of the Kohn- Sham coefficient and an exchange-correlation contribution. The formalism is applied to the single- impurity Anderson model for which approximate exchange-correlation functionals are suggested for temperatures both above and below the Kondo temperature. A certain structural property of the exchange-correlation potentials in the Coulomb blockade regime allows to recover an earlier result expressing the Seebeck coefficient in terms of quantities of equilibrium density functional theory. The numerical i-DFT results are compared to calculations with the numerical renormalization group over a wide range of temperatures finding a reasonable agreement while i-DFT comes at a much lower computational cost.

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