Using a novel approach to calculate optical properties of strongly correlated systems, we address the old question of the physical origin of the $\alpha \to \gamma$ transition in Ce. We find that the Kondo collapse model, involving both the $f$ and the $spd$ electrons, describes the optical data better than a Mott transition picture involving the $f$ electrons only. Our results compare well with existing experiments on thin films. We predict the full temperature dependence of the optical spectra and find the development of a hybridization pseudogap in the vicinity of the $\alpha \to \gamma$ phase transition.

• Received 2 March 2004

DOI:https://doi.org/10.1103/PhysRevLett.94.036401