Electronic structure and magnetic anisotropy of CrO_2
  The problem of importance of strong correlations for the electronic structure, transport and magnetic properties of half--metallic ferromagnetic CrO_2 is addressed by performing density functional electronic structure calculations in the local spin density approximation (LSDA) as well as using the LSDA+U method. It is shown that the corresponding low--temperature experimental data are best fitted without accounting for the Hubbard U corrections. We conclude that the ordered phase of CrO$_2 is weakly correlated. 
A. Toropova, G. Kotliar, S. Y. Savrasov and V.S. Oudovenko