Collective mode dispersions of organic chain compounds

Open Physics ◽  
2010 ◽  
Vol 8 (3) ◽  
Author(s):  
Željana Lošić ◽  
Paško Županović
Keyword(s):  
Collective Mode ◽  
Random Phase ◽  
Tight Binding ◽  
Three Dimensional ◽  
Plasmon Mode ◽  
Optical Data ◽  
Electron Interaction ◽  
Coulomb Interactions ◽  
One Dimensional ◽  
Donor And Acceptor

AbstractWe investigate the collective mode dispersions for the tight-binding dielectric matrix with two one-dimensional electron bands per donor and acceptor chains, and the three-dimensional long-range Coulomb electron-electron interaction within the random phase approximation. The hybridized collective modes are the result of the strong coupling between the intraband plasmon and the interband dipolar modes due to strong dipole Coulomb interactions. Our calculations show the existence of the low-energy renormalized plasmon mode above the electron-hole quasi-continuum in the long wavelength limit. The obtained modes are brought into correspondence with the optical data of quasi-one-dimensional organic conductor tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ). Namely, the renormalized plasmon and the dipolar mode are assigned to the observed excitations at respective energy scales of roughly 10 meV and 0.75 eV, explaining why lower excitation is eliminated while higher excitation persists below the temperature of the Peierls phase transition.

Energy-loss function of TTF-TCNQ

Open Physics ◽  
2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Željana Lošić
Keyword(s):  
Energy Loss ◽  
Loss Function ◽  
Random Phase ◽  
Three Dimensional ◽  
Spectral Weight ◽  
Electron Interaction ◽  
Energy Loss Function ◽  
One Dimensional ◽  
Long Wavelength ◽  
Donor And Acceptor

AbstractWe investigate the energy-loss function for a previously developed model of quasi-one-dimensional metals with two one-dimensional electron bands per donor and acceptor chains and the three-dimensional long-range Coulomb electron-electron interaction within the random phase approximation. It is essentially influenced by two hybridized collective modes which result from the strong coupling of the intraband plasmon and the interband dipolar modes. Our calculations show that the spectral weights of the renormalized plasmon and the dipolar mode dominate within the long wavelength limit, while for large longitudinal wave vectors the intraband electron-hole quasi-continuumgains some experimentally observable spectral weight as the second mode approaches it. The function obtained is brought into correspondence with the data of the quasi-one-dimensional organic conductor tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) obtained from electron energy-loss spectroscopy (EELS) measurements.

scholarly journals Photo-emission properties of quasi-one-dimensional conductors

2002 ◽  
Vol 12 (9) ◽  
pp. 53-56
Author(s):  
Z. Agic ◽  
P. Zupanovic ◽  
A. Bjelis
Keyword(s):  
Random Phase ◽  
Three Dimensional ◽  
Plasmon Mode ◽  
Luttinger Liquids ◽  
One Dimensional ◽  
Self Energy ◽  
Frequency Scale ◽  
Plasmon Frequency ◽  
The One ◽  
Experimental Findings

We calculate the self-energy of the one-dimensional electron band with the three-dimensional long-range Coulomb interaction within the random phase approximation, paying particular attention to the contribution coming from the electron scatterings on the collective plasmon mode. It is shown that the spectral density has a form of wide feature at the frequency scale of the plasmon frequency, without the presence of quasi-particle δ-peaks. The relevance of this result with respect to experimental findings and to the theory of Luttinger liquids is discussed.

Superconductivity of an interacting anyon system

1991 ◽  
Vol 05 (10) ◽  
pp. 1589-1596 ◽  
Author(s):  
J. Yang ◽  
W. P. Su ◽  
C. S. Ting
Keyword(s):  
Random Phase Approximation ◽  
Collective Mode ◽  
Collective Excitation ◽  
Random Phase ◽  
Meissner Effect ◽  
Plasmon Mode ◽  
Long Wavelength ◽  
Roton Minimum ◽  
Repulsive Coulomb ◽  
Plasmon Spectrum

A study of the Meissner effect and the plasmon spectrum for an interacting anyon system is presented. It is shown that the Meissner effect is not sensitive to, and still persists in, the presence of repulsive Coulomb interaction among anyons. Within the random phase approximation we show that the collective excitation of the system in the long-wavelength limit corresponds to the plasmon mode of a two dimensional interacting electron gas and it does not depend on the statistics associated with the anyons. There is a roton minimum of the collective mode at a finite value of the wavevector. A similar analysis on an array of layered anyon systems is also reported.

Structure and function of neural networks in the retina

1988 ◽  
Vol 46 ◽  
pp. 26-27
Author(s):  
Peter Sterling
Keyword(s):  
Ganglion Cells ◽  
Three Dimensional ◽  
Structure And Function ◽  
Synaptic Connections ◽  
Visual Axis ◽  
One Dimensional ◽  
Cat Retina ◽  
Ultrathin Sections ◽  
And Function ◽  
Insight Into

The synaptic connections in cat retina that link photoreceptors to ganglion cells have been analyzed quantitatively. Our approach has been to prepare serial, ultrathin sections and photograph en montage at low magnification (˜2000X) in the electron microscope. Six series, 100-300 sections long, have been prepared over the last decade. They derive from different cats but always from the same region of retina, about one degree from the center of the visual axis. The material has been analyzed by reconstructing adjacent neurons in each array and then identifying systematically the synaptic connections between arrays. Most reconstructions were done manually by tracing the outlines of processes in successive sections onto acetate sheets aligned on a cartoonist's jig. The tracings were then digitized, stacked by computer, and printed with the hidden lines removed. The results have provided rather than the usual one-dimensional account of pathways, a three-dimensional account of circuits. From this has emerged insight into the functional architecture.

Exploring the Multidimensional Facets of Authoritarianism: Authoritarian Aggression and Social Dominance Orientation

2008 ◽  
Vol 67 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Stefano Passini
Keyword(s):  
Social Dominance ◽  
Factor Model ◽  
Three Dimensional ◽  
Social Dominance Orientation ◽  
Model Fit ◽  
Regression Analyses ◽  
One Dimensional ◽  
Confirmatory Factor ◽  
The One ◽  
Better Than

The relation between authoritarianism and social dominance orientation was analyzed, with authoritarianism measured using a three-dimensional scale. The implicit multidimensional structure (authoritarian submission, conventionalism, authoritarian aggression) of Altemeyer’s (1981, 1988) conceptualization of authoritarianism is inconsistent with its one-dimensional methodological operationalization. The dimensionality of authoritarianism was investigated using confirmatory factor analysis in a sample of 713 university students. As hypothesized, the three-factor model fit the data significantly better than the one-factor model. Regression analyses revealed that only authoritarian aggression was related to social dominance orientation. That is, only intolerance of deviance was related to high social dominance, whereas submissiveness was not.

scholarly journals Cobalt-based magnetic Weyl semimetals with high-thermodynamic stabilities

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Wei Luo ◽  
Yuma Nakamura ◽  
Jinseon Park ◽  
Mina Yoon
Keyword(s):  
Tight Binding ◽  
Three Dimensional ◽  
Interlayer Coupling ◽  
First Principles Calculation ◽  
Optimization Approach ◽  
Binding Model ◽  
Nodal Lines ◽  
Weyl Semimetal ◽  
Topological Quantum ◽  
First Time

AbstractRecent experiments identified Co3Sn2S2 as the first magnetic Weyl semimetal (MWSM). Using first-principles calculation with a global optimization approach, we explore the structural stabilities and topological electronic properties of cobalt (Co)-based shandite and alloys, Co3MM’X2 (M/M’ = Ge, Sn, Pb, X = S, Se, Te), and identify stable structures with different Weyl phases. Using a tight-binding model, for the first time, we reveal that the physical origin of the nodal lines of a Co-based shandite structure is the interlayer coupling between Co atoms in different Kagome layers, while the number of Weyl points and their types are mainly governed by the interaction between Co and the metal atoms, Sn, Ge, and Pb. The Co3SnPbS2 alloy exhibits two distinguished topological phases, depending on the relative positions of the Sn and Pb atoms: a three-dimensional quantum anomalous Hall metal, and a MWSM phase with anomalous Hall conductivity (~1290 Ω−1 cm−1) that is larger than that of Co2Sn2S2. Our work reveals the physical mechanism of the origination of Weyl fermions in Co-based shandite structures and proposes topological quantum states with high thermal stability.

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