Modified f (R) gravity from scalar–tensor theory and inhomogeneous EoS dark energy

The reconstruction of f (R)-gravity is showed by using an auxiliary scalar field in the context of cosmological evolution, this development provides a way to reconstruct the form of the function f (R) for a given evolution of the Hubble parameter. In analogy, f (R)-gravity may be expressed by a perfect fluid with an inhomogeneous equation of state (EoS) that depends on the Hubble parameter and its derivatives. This mathematical equivalence that may confuse about the origin of the mechanism that produces the current acceleration, and possibly the whole evolution of the Hubble parameter, is shown here.