which makes it explicit that E[ρ] only depends on the charges q A . We may therefore equivalently use the notation E(q 1 , ..., q N ). Note that this equation has the familiar form of the original QEq formulation, with the slight difference that the hardness parameter in QEq implicitly includes the electrostatic idempotential 2γ AA √ π , whereas here η A only describes the non-classical (e.g. exchange-correlation) contributions to the hardness.