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1.
We study a lattice bipolaron on a staggered triangular ladder and triangular and hexagonal lattices with both long-range electron-phonon interaction and strong Coulomb repulsion using a novel continuous-time quantum Monte Carlo algorithm to solve the two-particle Coulomb-Fr?hlich model. The algorithm is preceded by an exact integration over phonon degrees of freedom, and as such is extremely efficient. The bipolaron effective mass and radius are computed. Bipolarons on lattices constructed from triangular plaquettes have a novel crablike motion, and are small but very light over a wide range of parameters. We discuss the conditions under which such particles may form a Bose-Einstein condensate with high transition temperature, proposing a route to room temperature superconductivity. 相似文献
2.
Theresa Hague Andrea Petroczi Paul LR Andrews James Barker Declan P Naughton 《Chemistry Central journal》2010,4(1):2
This is a correction to the following paper: Hague T, Petroczi A, Andrews PR, Barker J, Naughton DP: Determination of metal
ion content of beverages and estimation of target hazard quotients: a comparative study. Chem Central J 2008, 2:13. 相似文献
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The Lβ1, Lα1, 2 X-ray lines recorded for Zn vapour show that, as opposed to observations on the solid, the L2, L3 levels have equal widths. It indicates that an L2 hole Coster-Kronig decay is not allowed in the free atom. 相似文献
5.
J.P. Hague P.E. Kornilovitch A.S. Alexandrov 《Journal of Physics and Chemistry of Solids》2008,69(12):3304-3306
We study the Coulomb-Fröhlich model on a triangular lattice, looking in particular at states with angular momentum. We examine a simplified model of crab bipolarons with angular momentum by projecting onto the low energy subspace of the Coulomb-Fröhlich model with large phonon frequency. Such a projection is consistent with large long-range electron-phonon coupling and large repulsive Hubbard U. Significant differences are found between the band structure of singlet and triplet states: The triplet state (which has a flat band) is found to be significantly heavier than the singlet state (which has mass similar to the polaron). We test whether the heavier triplet states persist to lower electron-phonon coupling using continuous time quantum Monte Carlo (QMC) simulation. The triplet state is both heavier and larger, demonstrating that the heavier mass is due to quantum interference effects on the motion. We also find that retardation effects reduce the differences between singlet and triplet states, since they reintroduce second order terms in the hopping into the inverse effective mass. 相似文献
6.
C.F. Hague J.-M. Mariot J.J. Gallet 《Applied Physics A: Materials Science & Processing》1997,65(2):141-146
Accepted: 6 March 1997 相似文献
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Rueff JP Itié JP Taguchi M Hague CF Mariot JM Delaunay R Kappler JP Jaouen N 《Physical review letters》2006,96(23):237403
We report on the most complete investigation to date of the -electron properties at the transition in elemental Ce by resonant inelastic x-ray scattering (RIXS). The Ce 2p3d-RIXS spectra were measured directly in the bulk material as a function of pressure through the transition. The spectra were simulated within the Anderson impurity model. The occupation number n(f) and f double occupancy were derived from the calculations in both gamma and alpha phases in the ground state. We find that the electronic structure changes result mainly from band formation of 4f electrons which concurs with reduced electron correlation and increased Kondo screening at high pressure. 相似文献
9.
Patmore NJ Hague C Cotgreave JH Mahon MF Frost CG Weller AS 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(9):2088-2098
Four Lewis acidic silver phosphane complexes partnered with [1-closo-CB(11)H(12)](-) and [1-closo-CB(11)H(6)Br(6)](-) have been synthesised and studied by solution NMR and solid-state X-ray diffraction techniques. In the complex [Ag(PPh(3))(CB(11)H(12))] (1), the silver is coordinated with the carborane by two stronger 3c-2e B-H-Ag bonds, one weaker B-H-Ag interaction and a very weak Ag.C(arene) contact in the solid state. In solution, the carborane remains closely connected with the [Ag(PPh(3))](+) fragment, as evidenced by (11)B chemical shifts. Complex 2 [Ag(PPh(3))(2)(CB(11)H(12))](2) adopts a dimeric motif in the solid state, each carborane bridging two Ag centres. In solution at low temperature, two distinct complexes are observed that are suggested to be monomeric [Ag(PPh(3))(2)][CB(11)H(12)] and dimeric [Ag(PPh(3))(2)(CB(11)H(12))](2). With the more weakly coordinating anion [CB(11)H(6)Br(6)](-) and one phosphane, complex 3 [Ag(PPh(3))(CB(11)H(6)Br(6))] is isolated. Complex 4, [Ag(PPh(3))(2)(CB(11)H(6)Br(6))], has been characterised spectroscopically. All of the complexes have been assessed as Lewis acids in the hetero-Diels-Alder reaction of N-benzylideneaniline with Danishefsky's diene. Exceptionally low catalyst loadings for this Lewis acid catalysed reaction are required (0.1 mol %) coupled with turnover frequencies of 4000 h(-1) (quantitative conversion to product after 15 minutes using 3 at room temperature). Moreover, the reaction does not occur in rigorously dry solvent as addition of a substoichiometric amount of water (50 mol %) is necessary for turnover of the catalyst. It is suggested that a Lewis assisted Br?nsted acid is formed between the water and the silver. The effect of changing the counterion to [BF(4)](-), [OTf](-) and [ClO(4)](-) has also been studied. Significant decreases in reaction rate and final product yield are observed on changing the anion from [CB(11)H(6)Br(6)](-), thus demonstrating the utility of weakly coordinating carborane anions in organic synthesis. 相似文献
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