  Thermoelectric effects, measured by the Seebeck coefficients, refer to the
phenomena in which a temperature difference or gradient imposed across a
thermoelectric material induces an electrical potential difference or gradient,
and vice versa, enabling the direct conversion of thermal and electric
energies. All existing understanding and first-principles calculations of
Seebeck coefficients have been based on the Boltzmann kinetic transport theory.
Here we demonstrate that the Seebeck coefficient is a well-defined
thermodynamic quantity that can be determined from the change in the chemical
potential of electrons induced by the temperature change and thus can be
efficiently computed solely based on the electronic density of states through
first-principles calculations at different temperatures. The proposed approach
is demonstrated using the prototype PbTe and SnSe thermoelectric materials. The
proposed thermodynamic approach dramatically simplifies the calculations of
Seebeck coefficients, making it possible to search for high performance
thermoelectric materials using high-throughput first-principles calculations.
