Exact exchange-correlation treatment of dissociated H(2) in density functional theory.

Whereas the wave function of the dissociated H(2) molecule is easily obtained, an exact treatment of this system has not yet been given in density functional theory. We propose an orbital dependent exchange-correlation functional that yields this exact Kohn-Sham solution. This type of functional offers an alternative to local-density and generalized gradient approximations and the prospects are indicated for treating with it some outstanding problems in density functional theory.