This paper deals with the ground state of an interacting electron gas in an external potential . It is proved that there exists a universal functional of the density, , independent of , such that the expression has as its minimum value the correct ground-state energy associated with . The functional is then discussed for two situations: (1) , , and (2) with arbitrary and . In both cases can be expressed entirely in terms of the correlation energy and linear and higher order electronic polarizabilities of a uniform electron gas. This approach also sheds some light on generalized Thomas-Fermi methods and their limitations. Some new extensions of these methods are presented.
- Received 18 June 1964
- Published in the issue dated November 1964
© 1964 The American Physical Society