  Density functional calculations can fail for want of an accurate
exchange-correlation approximation. The energy can instead be extracted from a
sequence of density functional calculations of conditional probabilities
(CP-DFT). Simple CP approximations yield usefully accurate results for
two-electron ions, the hydrogen dimer, and the uniform gas at all temperatures.
CP-DFT has no self-interaction error for one electron, and correctly
dissociates H2, both major challenges. For warm dense matter, classical CP-DFT
calculations can overcome the convergence problems of Kohn-Sham DFT.
