This paper provides an overview of the title paper by Perdew, Parr, Levy and Balduz [Phys Rev Lett 49:1691 (1982)]. The title paper extended density functional theory to fractional electron number by an ensemble approach and proved that the energy is a series of straight lines interpolating its values at integer numbers of electrons. It also established that the highest-occupied exact Kohn-Sham orbital energy is the negative of the ionization energy, and showed that the exchange-correlation potential jumps by a constant as the number of electrons increases by an integer. These results are fundamental and continue to inspire developments in density functional theory.
- Density functional theory
- Derivative discontinuity
- Exchange-correlation functional
- Fractional number of electrons
- Self interaction error
ASJC Scopus subject areas
- Physical and Theoretical Chemistry