  We showcase the advantages of orbital-free density-potential functional
theory (DPFT), a more flexible variant of Hohenberg-Kohn density functional
theory. DPFT resolves the usual trouble with the gradient-expanded kinetic
energy functional by facilitating systematic semiclassical approximations in
terms of an effective potential energy that incorporates all interactions. With
the aid of two systematic approximation schemes we demonstrate that DPFT is not
only scalable, universally applicable in both position and momentum space, and
allows kinetic and interaction energy to be approximated consistently, but can
also compete with highly accurate, yet restricted, methods. As two- and
three-dimensional geometries are extensively covered elsewhere, our focus here
is on one-dimensional settings, with semiclassical observables systematically
derived from both the Wigner function formalism and a split-operator approach.
The high quality of our results for Fermi gases in Morse potentials invites the
use of DPFT for describing more exotic systems, such as trapped large-spin
fermion mixtures with contact or dipole-dipole interactions.
