Variational Wigner-Kirkwood $\hbar$ expansion
Résumé
The variational content of the Wigner–Kirkwood ℏ expansion of the density matrix is analyzed in mean field approximation. A new variational method based on a strict expansion of the energy density in powers of ℏ is established. It is applied to the case of fermions moving in an external potential, as well as to the self-consistent problem in semi-infinite matter. The standard density functional theory is reviewed and contrasted with the new method. (Elsevier)