Abstract
It is shown that the variation of the total energy, as constructed in density-functional theory, with respect to an orbital occupation is equal to the eigenvalue of that orbital, independent of the detailed form of the exchange-correlation functional. This leads to a rigorous connection between the ground-state energies of - and ()-particle systems, which is useful in the calculation of certain excitation energies.
- Received 14 June 1978
DOI:https://doi.org/10.1103/PhysRevB.18.7165
©1978 American Physical Society