Strong correlation in DFT at finite temperatures: the case of the Hubbard dimer.

Density Functional Theory and its finite-temperature extension are a workhorse for electronic structure calculations and the study of warm dense matter properties. In its Kohn-Sham formulation, much effort is devoted to approximate exchange-correlation effects, often neglecting completely temperature effects. 

Using as reference an infinitely interacting system, we make use of a half-filled Hubbard model at finite temperature to gather insights on the decorrelation energy. The so-obtained strongly interacting Mermin functional displays a non-trivial temperature dependence, which could help improve understanding of the role of temperature corrections in exchange-correlation effects.