Chemical accuracy and room temperature

Chemical accuracy is $$\pu{2E-2 eV}$$ but room temperature $$\pu{20 ^\circ C}$$ is $$\pu{2.5E-2 eV}$$, so why is it not necessary to take into account thermal effects in DFT? I understood (maybe wrongly) that chemical accuracy is the precision we want on electronic energies for one atom or one molecule.

• $\mathrm{k_B T}$ at room temperature is about $\mathrm{25\ meV}$. Sep 9 '20 at 11:52
• Right, sorry ! still it's the same order of magnitude than chemical accuracy... so why it's not necessary to take into account thermal effects in DFT ?
– Jom
Sep 9 '20 at 12:37
• About precission and accuracy, see this Sep 9 '20 at 14:26
• DFT can be used to describe electronic structure (and more). It is used nowadays with different functionals, which I like to call density functional approximations (DFA). Most of them have errors beyond chemical accuracy. And there are further approximations, which could handle thermal effects. I'm not quite sure whether I understand the question right, maybe it would be helpful if you could add some more context. In any case: Welcome to Chemistry.se! Sep 9 '20 at 14:51
• What is chemical accuracy, and why is it 20meV?
– Karl
Sep 9 '20 at 18:46