  The ground state properties of the one-dimensional Kondo lattice with an f^2
configuration at each site are studied by the density matrix renormalization
group method. At half-filling, competition between the Kondo exchange J and the
antiferromagnetic intra f-shell exchange I leads to reduction of energy gaps
for spin, quasi-particle and charge excitations. The attractive force among
conduction electrons is induced by the competition and the bound state is
formed. As J/I increases the f^2 singlet gives way to the Kondo singlet as the
dominant local correlation. The remarkable change of the quasi-particle gap is
driven by the change of the spin-1/2 excitation character from the itinerant
one to the localized one. Possible metal-insulator transition is discussed
which may occur as the ratio J/I is varied by reference to mean-field results
in the f^2 lattice system and the two impurity Kondo system.
