  Inter-Coulombic decay (ICD) resonances in the photoionization of Cl@C60
endofullerene molecule are calculated using a perturbative density functional
theory (DFT) method. This is the first ICD study of an open shell atom in a
fullerene cage. Three classes of resonances are probed: (i) Cl inner vacancies
decaying through C60 outer continua, (ii) C60 inner vacancies decaying through
Cl outer continua, and (iii) inner vacancies of either system decaying through
the continua of Cl-C60 hybrid levels, the hybrid Auger-ICD resonances.
Comparisons with Ar@C60 results reveal that the properties of hybrid Auger-ICD
resonances are affected by the extent of level hybridization.
