We classify circle actions on
F-spaces X with Hod(X; ℚ) = 0 up to equivariant rational homotopy equivalence by
the concept of g-points in the spectrum of the cohomology ring of Baut0(X). In
the case of circle actions on closed oriented manifolds X with the rational
cohomology of flag varieties K∕T this gives a generalization of the rational
homotopy classification of linear (or homomorphic) circle actions to nonlinear
S1-actions.