The exact expression for the Fermi potential yielding the Hartree-Fock electron density within an orbital-free density functional formalism is derived. The Fermi potential, which is defined as that part of the potential that depends on the particles' nature, is in this context given as the sum of the Pauli potential and the exchange potential. The exact exchange potential for an orbital-free density functional formalism is shown to be the Slater potential.
Funding Agencies|Alexander von Humboldt foundation in form of a Feodor Lynen-fellowship; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009 00971]; NSERC and Compute Canada