A Design Methodology for Early Education Facility Prototypes in Hawai‘i.

D.Arch. Thesis. University of Hawaiʻi at Mānoa 2017

Electron correlations and bond-length fluctuations in copper oxides: from Zhang--Rice singlets to correlation bags

We perform first principles, multiconfiguration calculations on clusters including several CuO$_6$ octahedra and study the ground-state electron distribution and electron--lattice couplings when holes are added to the undoped $d^9 p^6$ configuration. We find that the so-called Zhang--Rice state on a single CuO$_4$ plaquette is nearly degenerate with a state whose leading configuration is of the form Cu $d^9$-- O $p^5$-- Cu $d^9$. A strong coupling between the electronic and nuclear motion gives rise to large inter-site charge transfer effects for half-breathing displacements of the oxygen ions. Under the assumption of charge segregation into alternating hole-free and hole-rich stripes of Goodenough \cite{jbg_02,jbg_03}, our results seem to support the vibronic mechanism and the traveling charge-density wave model from Refs.\cite{jbg_02,jbg_03} for the superconductivity in copper oxides.Comment: submitted to Phys. Rev.

Renormalization of the quasiparticle hopping integrals by spin interactions in layered copper oxides

Holes doped within the square CuO2 network specific to the cuprate superconducting materials have oxygen 2p character. We investigate the basic properties of such oxygen holes by wavefunction-based quantum chemical calculations on large embedded clusters. We find that a 2p hole induces ferromagnetic correlations among the nearest-neighbor Cu 3d spins. When moving through the antiferromagnetic background the hole must bring along this spin polarization cloud at nearby Cu sites, which gives rise to a substantial reduction of the effective hopping parameters. Such interactions can explain the relatively low values inferred for the effective hoppings by fitting the angle-resolved photoemission data. The effect of the background antiferromagnetic couplings of renormalizing the effective nearest-neighbor hopping is also confirmed by density-matrix renormalization-group model Hamiltonian calculations for chains and ladders of CuO4 plaquettes

Optical conductivity in the CuO double chains of PrBa_2Cu_4O_8: Consequences of charge fluctuation

We calculate the optical conductivity of the CuO double chains of PrBa$_2$Cu$_4$O$_8$ by the mean-field approximation for the coupled two-chain Hubbard model around quarter filling. We show that the $\sim$40 meV peak structure, spectral shape, and small Drude weight observed in experiment are reproduced well by the present calculation provided that the stripe-type charge ordering presents. We argue that the observed anomalous optical response may be due to the presence of stripe-type fluctuations of charge carriers in the CuO double chains; the fast time scale of the optical measurement should enable one to detect slowly fluctuating order parameters as virtually a long-range order.Comment: 7 pages, 5 eps figure

Basic properties of three-leg Heisenberg tube

We study three-leg antiferromagnetic Heisenberg model with the periodic boundary conditions in the rung direction. Since the rungs form regular triangles, spin frustration is induced. We use the density-matrix renormalization group method to investigate the ground state. We find that the spin excitations are always gapped to remove the spin frustration as long as the rung coupling is nonzero. We also visibly confirm spin-Peierls dimerization order in the leg direction. Both the spin gap and the dimerization order are basically enhanced as the rung coupling increases.Comment: 4 pages, 2 figure

Redescription of the \u3ci\u3eAllomyia renoa\u3c/i\u3e (Milne) female and association and description of the male and larva (Trichoptera: Apataniidae)

Allomyia renoa (Milne, 1935) (Trichoptera: Apataniidae) was described from six females. The male association is verified in this paper. The original type locality information is limited: “Reno, Nev., ‘78, Morrison”. An Allomyia Banks population found at Mount Rose in Washoe County, Nevada, was compared to the A. renoa type material and found to be the conspecific. Figures, descriptions and distribution of male, female, pupal and larval A. renoa are provided

Redescription of the \u3ci\u3eAllomyia renoa\u3c/i\u3e (Milne) female and association and description of the male and larva (Trichoptera: Apataniidae)

Allomyia renoa (Milne, 1935) (Trichoptera: Apataniidae) was described from six females. The male association is verified in this paper. The original type locality information is limited: “Reno, Nev., ‘78, Morrison”. An Allomyia Banks population found at Mount Rose in Washoe County, Nevada, was compared to the A. renoa type material and found to be the conspecific. Figures, descriptions and distribution of male, female, pupal and larval A. renoa are provided

Coexistence of distinct charge fluctuations in θ\theta-(BEDT-TTF)2_2X

Using the Lanczos exact-diagonalization and density-matrix renormalization group methods, we study the extended Hubbard model at quarter filling defined on the anisotropic triangular lattice. We focus on charge ordering (CO) phenomena induced by onsite and intersite Coulomb interactions. We determine the ground-state phase diagram including three CO phases, i.e., diagonal, vertical, and three-fold CO phases, based on the calculated results of the hole density and double occupancy. We also calculate the dynamical density-density correlation functions and find possible coexistence of the diagonal and three-fold charge fluctuations in a certain parameter region where the onsite and intersite interactions compete. Furthermore, the characteristic features of the optical conductivity for each CO phase are discussed.Comment: 9 pages, 7 figure