DFT uses the Kohn-Sham approximation which is single particle and is a ground state theory. There’s definitely been research along the lines you bring up in qua

DFT uses the Kohn-Sham approximation which is single particle and is a ground state theory. There’s definitely been research along the lines you bring up in quantum chemistry but not in DFT. You want to look at the Levy-Lieb density and maybe some of Mazziotti’s papers