  We use the density matrix renormalization group method to study the interplay
of the localized and itinerant behaviors in the one-dimensional
Kondo-Heisenberg model. We find signatures of simultaneously localized and
itinerant behaviors of the local spins and attribute this duality to their
simultaneous entanglement within the spin chain and with conduction electrons
due to incomplete hybridization. We propose a microscopic definition of the
hybridization parameter that measures this "partial" itinerancy. Our results
provide a microscopic support for the dual nature of f-electrons and the
resulting two-fluid behavior widely observed in heavy electron materials.
