  The single-impurity Anderson model is studied within the i-DFT framework, a
recently proposed extension of density functional theory (DFT) for the
description of electron transport in the steady state. i-DFT is designed to
give both the steady current and density at the impurity, and it requires the
knowledge of the exchange-correlation (xc) bias and on-site potential (gate).
In this work we construct an approximation for both quantities which is
accurate in a wide range of temperatures, gates and biases, thus providing a
simple and unifying framework to calculate the differential conductance at
negligible computational cost in different regimes. Our results mark a
substantial advance for DFT and may inform the construction of functionals
applicable to other correlated systems.
