Investigation of the gamma-alpha phase transition in cerium by Compton scattering

The change in Compton profile between pure phase ..gamma.. and ..cap alpha.. cerium has been measured and compared to electron momentum distributions calculated on the basis of renormalized-free-atom and tight-binding models. It turned out that any kind of promotion of the 4f electron into the conduction band is in striking contradiction to the experiment. The main contribution of the measured difference profile is due to the increased conduction-electron density in the collapsed phase.