A new paper has been accepted for publication and is now online on the J. Chem. Phys. website [J. Chem. Phys. 12, vol. 134, 164102 (2011)]. The article “A natural orbital functional for multiconfigurational states” by M. Piris, X. Lopez, F. Ruipérez, J. M. Matxain, and J. M. Ugalde can now be accesed at doi: 10.1063/1.3582792