Physical Review A
Equations satisfied by the kinetic-energy functional and its derivatives
Daniel P. Joubert
Abstract
A set of equations that the kinetic-energy functional of a system of noninteracting fermions and its derivatives must satisfy are derived. These complement the hierarchy of equations derived by Kugler [Phys. Rev. A 41, 3489 (1990)]. As a consequence of these equations the kinetic energy can be expressed in terms of any of its functional derivatives.