# Thermal

The linear response tensor in the kpm method is generalized to account for thermal responses.
This is done by considering the generalized Kubo formula described in reference [5].
To do so a second energy integration is performed with weighting the integrand in the linear response
with a temperature dependent factor given by eq (8) of [5].
To simplify the implementation of (8) the derivative of the Fermi distribution with respect to the chemical potential is taken in units of (1/T) with T being taken in units of energy. Hence, the thermal response is given in units of the universal thermal conductance quantum.
A parameter thermal_response, is introduced in the underlying classes and functions as an option. So it can be activated by the user, while it's set at None by default.

This linear response can be used for computing the Nernst and the spin Nernst effects ..

[5] Phys. Rev. Lett. 97, 026603 (2006) https://arxiv.org/abs/cond-mat/0604561