Approximation of the potential in scalar field dark energy models

We study the nature of potentials in scalar field based models for dark energy - with both canonical and noncanonical kinetic terms. We calculate numerically, and using an analytic approximation around a≈1, potentials for models with constant equation-of-state parameter wφ. We find that for a wide range of models with canonical and noncanonical kinetic terms there is a simple approximation for the potential that holds when the scale factor is in the range 0.6a1.4. We discuss how this form of the potential can also be used to represent models with nonconstant wφ and, hence, how it could be used in reconstruction from cosmological data.