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Self-Consistent Cluster Embedding Calculation Method And The Electronic Structure Of Nickel Oxide And Cobalt Oxide., Haoping Zheng
Self-Consistent Cluster Embedding Calculation Method And The Electronic Structure Of Nickel Oxide And Cobalt Oxide., Haoping Zheng
LSU Historical Dissertations and Theses
We present a self-consistent cluster embedding method to study the electronic structure of solids by ab initio, local spin density functional calculations. A theoretical discussion from the viewpoint of total energy is given, and a definition of the total energy for an embedded cluster is introduced. We have constructed a general LCGO cluster-embedding program package, and developed a procedure to simulate the spin disordered states with local antiferromagnetic (AF) order. The electronic structures of NiO and CoO are studied by this method with a high quality basis set. The two materials show similar antiferromagnetic insulating ground states with both localized …
Magnetic Field Dependence Of The Specific Heat Of A Heavy Fermion System., Jai Won Kim
Magnetic Field Dependence Of The Specific Heat Of A Heavy Fermion System., Jai Won Kim
LSU Historical Dissertations and Theses
One of the distinguishing characteristics of heavy Fermion materials is the extraordinarily large size of the electronic specific heat at low temperatures. It is also observed that in some cases, the specific heat is reduced drastically by an external magnetic field. We show that this behavior can be simulated by using the non-degenerate lattice Anderson model on a 4-site tetrahedral cluster. Interactions included in the model are the on-site Couloumb repulsion between electrons in the f-orbital and the off-site spin conserving hybridization between electrons in the conduction and the f-orbitals. Our calculation is done by using the exact diagonalization method. …
Dynamic Properties Of Interacting Electrons., Lun Tan
Dynamic Properties Of Interacting Electrons., Lun Tan
LSU Historical Dissertations and Theses
The spectral weight functions and the optical conductivity of a highly correlated electronic system described by a simple Hubbard model are studied. The calculations are carried out for a small system, a cubic cluster of eight sites, by means of exact diagonalization using symmetrized basis functions. The spectral weight functions of a single hole (or electron) placed in an otherwise half-filled band are obtained. The density of states at different interaction strengths, ranging from weak to strong couplings, is studied. We observe the spreading of the spectral weight associated with some single-particle eigenstates over a large range of energies, and …