  To clarify the role of the Kondo effect in screening local magnetic moments
of Plutonium 5f--electrons as well as its competition to the RKKY interactions
we use a combination of density functional theory with static Hartree Fock and
dynamic Hubbard 1 approximations to calculate the strength of both the Kondo
exchange, J_K, and of the RKKY exchange, J_RKKY, couplings for Pu{1-x}Am{x}
system as a function of x. We find that J_K increases despite the atomic volume
gets larger with the Am doping due to unexpected enhancement of hybridization
between f and conduction electrons in the vicinity of the Fermi level. At the
same time, the RKKY exchange is shown to reduce smoothly with increasing x. Our
results imply that the Kondo effect should be robust against the increase in
interatomic spacing of this alloy.
