On the Newtonian Limit in Gravity Models with Inverse Powers of R

I reconsider the problem of the Newtonian limit in nonlinear gravity models in the light of recently proposed models Lgrav ∼ √−gf(R) with inverse powers of R. Expansion around a maximally symmetric local background with curvature scalar R0 > 0 gives the correct Newtonian limit on length scales ≪ R 0 if the gravitational Lagrangian √−gf(R) satisfies |f(R0)f (R0)| ≪ 1, and I propose two models with f ′′(R0) = 0.