title: Dependence of Response Functions and Orbital Functionals on Occupation Numbers.
abstract: Explicitly orbital-dependent approximations to the exchange-correlation energy functional of density functional theory typically not only depend on the single-particle Kohn-Sham orbitals but also on their occupation numbers in the ground-state Slater determinant. The variational calculation of the corresponding exchange-correlation potentials with the optimized effective potential (OEP) method therefore also requires a variation of the occupation numbers with respect to a variation in the effective single-particle potential, which is usually not taken into account. Here it is shown under which circumstances this procedure is justified.
authors.affiliation: Institut für Theoretische Physik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Kurth
authors.affiliation: Institut für Theoretische Physik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany.
authors.forename: C R
authors.initials: CR
authors.lastname: Proetto
authors.affiliation: Institut für Theoretische Physik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Capelle