NUMERICAL SIMULATIONS OF STRONGLY CORRELATED SYSTEMS - AN IMPURITY INONE-DIMENSION

The ground state properties of a single substitutional impurity in a s trongly correlated host are studied using exact diagonalisation. Stron gly interacting electrons are modeled by a repulsive Hubbard model. Bo th magnetic and non-magnetic impurities have been studied. Ic is obser ved that the local moment phase on the impurity is stabilized due to r epulsive interactions amongst the electrons. A scalar impurity (either with a double occupancy or a static vacancy) is seen to induce a loca l moment on the neighbouring sites for fillings close to half filling. Static spin and charge correlation functions reflect a non-Fermi liqu id character for both kinds of impurities, scalar and magnetic. A comp lete healing of the chain in presence of a magnetic impurity is seen a t half filling. Away from half filling, such healing is seen only in t he spin sector. Finally, we observe that the static spin and charge co rrelation functions for a magnetic impurity and a static vacancy are i dentical at quarter filling.