“…It turns out [1] that the energy functional behaves no less rigidly when the Sasaki metric h 0,0 is replaced by h 1,1 or h 2,0 ; however, other members of C G permit greater flexibility. In [2], a harmonic vector field on the Riemannian manifold (M, g) was defined to be a harmonic section of T M with respect to the Riemannian metric g on M and some h p,q ∈ C G ; classifications of harmonic vector fields were then obtained for conformal gradient fields and Killing fields on non-flat Riemannian space forms. Typically (but not invariably) a harmonic vector field is metrically unique; that is, it picks a unique h p,q ∈ C G .…”