• Dirac matrix;
  • density;
  • diffraction


The idempotent Dirac single-particle (s) density matrix γs(r,r′) as a functional of a given one-body potential V(r) was constructed to all orders in perturbation theory by March and Murray, some four and a half decades ago. While the subsequent theorems of DFT ensure that V is a functional of the ground-state density ρ, only recently has V been written explicitly as a functional of the Dirac density matrix γs. In the present study, both functionals γs[ρ] and γs[V] are studied; first for some model potentials V and somewhat then more generally in terms of partial differential equations. This later procedure should open up a route to treat numerically molecules of biophysical interest, provided the ground-state electron density ρ(r) is initially determined from diffraction experiments. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007