The bifunctional formalism: an alternative treatment of density functionals

Abstract The bifunctional formalism presents an alternative how to obtain the functional value from its derivative by exploiting homogeneous density scaling. In dependence of is suppressed. Consequently, those derivatives have be treated as formal derivatives. For a pointwise correspondence between true and derivative, expression yields same functional. Within can directly obtained (while itself remains unknown). Since are up constant uniquely defined, this approach allows for comparison approximate potentials reference potentials. This aspect especially important in field orbital-free theory, where burden kinetic energy. potential approximated directly, full control given over latter, consequently final electron densities variational procedure. Besides another concept introduced, dividing total non-interacting energy into known part remainder, called Pauli Only remainder requires further approximations. practical purposes sufficiently accurate application on atoms, molecular solid-state systems presented.