In 1964, Hohenberg and Kohn showed the opposite and far less obvious result \cite{hohenberg64}.
For a nondegenerate ground state, the ground-state charge density uniquely determines the external potential in which the electrons reside.
The proof presented by Hohenberg and Kohn proceeds by {\em reductio ad absurdum}.
In 1964, Hohenberg and Kohn showed the opposite and far less obvious result \cite{hohenberg64}.
For a nondegenerate ground state, the ground-state charge density uniquely determines the external potential in which the electrons reside.
The proof presented by Hohenberg and Kohn proceeds by {\em reductio ad absurdum}.