Browsing by Author "Okanigbuan Robinson O"

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    Effect Of Coulomb Interactions on The Amplitude Of Persistent Currents In One Dimensional Disordered Mesoscopic Metallic Rings
    (arXiv preprint, 2021) Onaiwu Kingsley Nosakhare; Okanigbuan Robinson O; Ehika S
    Persistent current is a small but perpetual electric current that flows in metallic rings in the absence of any applied source. We compute the persistent currents of one-dimensional disordered metallic rings of interacting electrons in the presence of impurity on lattices up to 8-sites at half-filling and also away from half-filling using the Lanczos algorithm. For the case of half-filling, we observe that both interaction and disorder suppress the amplitude of the persistent currents by localizing the electrons. However, in the presence of disorder and away from half-filling, the Coulomb interaction is observed to enhance the persistent current. Furthermore, in the half-filled case, there is a transition from metal to insulator as U is increased significantly. In addition, shifting away from half-filling, the system is observed to remain in the metallic state irrespective of the value of the Coulomb repulsion (U). The observations are quite in agreement with the results from other techniques.
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    Ground State Properties Of The One-Dimensional Hubbard Model: Symmetry Projected Variational Wave Function Approach
    (arXiv preprint, 2021) Onaiwu Kingsley Nosakhare; Okanigbuan Robinson O
    We use the C4v symmetry group of the 4*site Hubbard model to construct a ground state variational wave function of two- and four interacting electrons. In the limit U 0, ground state energies of the two- and four interacting electrons system is of the order *4t. The variational wave function of the four interacting electrons obtained using the B1 irreducible representation is valid for on-site Coulomb repulsion, while the one obtained using the A1 representation is valid for negative values of the Coulomb interaction. The system exhibits antiferromagnetic correlations.