  We investigate the effect of the Coulomb interaction, $U_{cf}$, between the
conduction and f electrons in the periodic Anderson model using the
density-matrix renormalization-group algorithm. We calculate the excitation
spectrum of the half-filled symmetric model with an emphasis on the spin and
charge excitations. In the one-dimensional version of the model it is found
that the spin gap is smaller than the charge gap below a certain value of
$U_{cf}$ and the reversed inequality is valid for stronger $U_{cf}$. This
behavior is also verified by the behavior of the spin and density correlation
functions. We also perform a quantum information analysis of the model and
determine the entanglement map of the f and conduction electrons. It is
revealed that for a certain $U_{cf}$ the ground state is dominated by the
configuration in which the conduction and f electrons are strongly entangled,
and the ground state is almost a product state. For larger $U_{cf}$ the sites
are occupied alternatingly dominantly by two f electrons or by two conduction
electrons.
