Study of the ionic Peierls-Hubbard model using density matrix renormalization group methods

Density matrix renormalization group methods are used to investigate the quantum phase diagram of a one-dimensional half-filled ionic Hubbard model with bond-charge attraction, which can be mapped from the Su-Schrieffer-Heeger-type electron-phonon coupling at the antiadiabatic limit. A bond order wave (dimerized) phase which separates the band insulator from the Mott insulator always exists as long as electron-phonon coupling is present. This is qualitatively different from that at the adiabatic limit. Our results indicate that electron-electron interaction, ionic potential and quantum phonon fluctuations combine in the formation of the bond-order wave phase

Block-block entanglement and quantum phase transitions in one-dimensional extended Hubbard model

In this paper, we study block-block entanglement in the ground state of one-dimensional extended Hubbard model. Our results show that the phase diagram derived from the block-block entanglement manifests richer structure than that of the local (single site) entanglement because it comprises nonlocal correlation. Besides phases characterized by the charge-density-wave, the spin-density-wave, and phase-separation, which can be sketched out by the local entanglement, singlet superconductivity phase could be identified on the contour map of the block-block entanglement. Scaling analysis shows that ${\rm log}_2(l)$ behavior of the block-block entanglement may exist in both non-critical and the critical regions, while some local extremum are induced by the finite-size effect. We also study the block-block entanglement defined in the momentum space and discuss its relation to the phase transition from singlet superconducting state to the charge-density-wave state.Comment: 8 pages, 9 figure

Entanglement and quantum phase transition in the extended Hubbard model

We study quantum entanglement in one-dimensional correlated fermionic system. Our results show, for the first time, that entanglement can be used to identify quantum phase transitions in fermionic systems.Comment: 5 pages, 4 figure

Silent cold-sensing neurons contribute to cold allodynia in neuropathic pain.

Neuropathic pain patients often experience innocuous cooling as excruciating pain. The cell and molecular basis of this cold allodynia is little understood. We used in vivo calcium imaging of sensory ganglia to investigate how the activity of peripheral cold-sensing neurons was altered in three mouse models of neuropathic pain: Oxaliplatin-induced neuropathy, partial sciatic nerve ligation and ciguatera poisoning. In control mice, cold-sensing neurons were few in number and small in size. In neuropathic animals with cold allodynia, a set of normally silent large-diameter neurons became sensitive to cooling. Many of these silent cold-sensing neurons responded to noxious mechanical stimuli and expressed the nociceptor markers NaV1.8 and CGRPα. Ablating neurons expressing NaV1.8 resulted in diminished cold allodynia. The silent cold-sensing neurons could also be activated by cooling in control mice through blockade of KV1 voltage-gated potassium channels. Thus silent cold-sensing neurons are unmasked in diverse neuropathic pain states and cold allodynia results from peripheral sensitization caused by altered nociceptor excitability

Quantum Chemistry, Anomalous Dimensions, and the Breakdown of Fermi Liquid Theory in Strongly Correlated Systems

We formulate a local picture of strongly correlated systems as a Feynman sum over atomic configurations. The hopping amplitudes between these atomic configurations are identified as the renormalization group charges, which describe the local physics at different energy scales. For a metallic system away from half-filling, the fixed point local Hamiltonian is a generalized Anderson impurity model in the mixed valence regime. There are three types of fixed points: a coherent Fermi liquid (FL) and two classes of self-similar (scale invariant) phases which we denote incoherent metallic states (IMS). When the transitions between the atomic configurations proceed coherently at low energies, the system is a Fermi liquid. Incoherent transitions between the low energy atomic configurations characterize the incoherent metallic states. The initial conditions for the renormalization group flow are determined by the physics at rather high energy scales. This is the domain of local quantum chemistry. We use simple quantum chemistry estimates to specify the basin of attraction of the IMS fixed points.Comment: 12 pages, REVTE

Effect of Calcium Supplementation on Gestation Length, Number Born Live, and Number of Stillborns

https://scholarworks.moreheadstate.edu/student_scholarship_posters/1016/thumbnail.jp

Effect of Gestation Length on Litter Size and Piglet Birth Weight

https://scholarworks.moreheadstate.edu/student_scholarship_posters/1019/thumbnail.jp

Correlation Induced Insulator to Metal Transitions

We study a spinless two-band model at half-filling in the limit of infinite dimensions. The ground state of this model in the non-interacting limit is a band-insulator. We identify transitions to a metal and to a charge-Mott insulator, using a combination of analytical, Quantum Monte Carlo, and zero temperature recursion methods. The metallic phase is a non-Fermi liquid state with algebraic local correlation functions with universal exponents over a range of parameters.Comment: 12 pages, REVTE

Hole dynamics in a quantum antiferromagnet beyond the retraceable path approximation

The one-hole spectral weight for two chains and two dimensional lattices is studied numerically using a new method of analysis of the spectral function within the Lanczos iteration scheme: the Lanczos spectra decoding method. This technique is applied to the $t-J_z$ model for $J_z \to 0$, directly in the infinite size lattice. By a careful investigation of the first 13 Lanczos steps and the first 26 ones for the two dimensional and the two chain cases respectively, we get several new features of the one-hole spectral weight. A sharp incoherent peak with a clear momentum dispersion is identified, together with a second broad peak at higher energy. The spectral weight is finite up to the Nagaoka energy where it vanishes in a non-analytic way. Thus the lowest energy of one hole in a quantum antiferromagnet is degenerate with the Nagaoka energy in the thermodynamic limit.Comment: RevTeX 3.0, SISSA preprint 156/93/CM/MB, 10 pages + postscript file appended, contains more accurate calculations in Fig.

In-plane Tunneling Spectrum into a [110]-Oriented High-TcT_c Superconductor in the Pseudogap Regime

Both the differential tunneling conductance and the surface local density of states (LDOS) of a [110]-oriented high-temperature superconductor in the pseudogap (PG) regime are studied theoretically. As a competing candidate for the mechanism of PG state, the charge-density wave (CDW), spin-density wave (SDW), $d$-density wave (DDW), and d-wave superconducting (DSC) orderings show distinct features in the tunneling conductance. For the CDW, SDW, and DSC orderings, the tunneling conductance approaches the surface LDOS as the barrier potential is increased. For the DDW ordering, we show for the first time that there exist midgap states at the [110] surface, manifesting themselves as a sharp zero-energy peak in the LDOS, as in the case of DSC ordering. However, due to the particle-hole pair nature of the DDW state, these states do not carry current, and consequently the one-to-one correspondence between the tunneling conductance and the surface LDOS is absent.Comment: 5 pages, 4 figures embedded in the tex