  Among the Cerium compounds, the heavier monochalcogenides CeY (Y=S,Se,Te) of
cerium provide a class of compounds which together with the heavier
monopnictides CeX (X=N,P,As,Sb,Bi) exhibit extremely interesting physical
properties. The hybridization of the partially delocalized f-electrons seems to
be responsible for the unusual properties, in particular the magnetic ones
which show great chemical sensitivity. As compared to the monopnictides, the
monochalcogenides have an additional anion p-electron which shifts the Fermi
energy into the p-region of the Cerium 5d-derived density of states, and which
should affect the hybridization function of the electrons in the conduction
band. In this contribution we analyze the 4f-hybridization function and the
crystal-field splittings of the compounds under study.
  KEY WORDS: Highly correlated systems, crystal fields, p-electron.
