ABSTRACT
Modem DFf is based on the celebrated theorem of Hohenberg and Kohn (HK) [ 4] which, for systems with nondegenerate ground states, may be summarized by the following three statements:
1. The ground-state density p uniquely determines the ground-state wave function 'li[p] as well as the external potential v = v[p]. As a consequence, any observable of a static many-particle system is a functional of its ground-state density.
