= Density functional variational principle
{title2=$E_0=\min_n\{F[n]+\int vn\}$}
The constrained-search functional $F[n]=\min_{\Psi\to n}\langle\Psi|T+W|\Psi\rangle$ is universal for a fixed interaction. Minimization of $F[n]+\int vn$ over admissible densities with the correct electron number gives the <ground-state energy>. Each trial density represents a constrained set of antisymmetric states, so minimizing over densities and their representing states recovers the ordinary <variational principle>. The admissible domain and possible degeneracy must be handled explicitly.
Back to article page
