Kinetic energy from a single Kohn-Sham orbital

We observe that the noninteracting kinetic energy, as a functional of the electron density ρ, may be obtained from a formula that contains only a single Kohn-Sham orbital, φi(r), where i is arbitrary. Specifically, Ts[ρ]=(−1/4)∫{∇2ϕi[ρ;r]/ϕi[ρ;r]}[3ρ(r)+r⋅∇ρ(r)]dr.