Electronic Phase Diagram of Mixed-Valence Gold Chloride

A comprehensive electronic phase diagram is derived for mixed-valence gold chloride Cs2Au2Cl6 by means of high-pressure Raman spectroscopy. At all the temperatures investigated (100K≤T≤300 K), applications of pressure induce a phase transition from the mlxed-valence (MV) state to a single-valence (SV) state. In the SV state, a broad Au-Cl stretching band appears at～400 cm^-1 below ～200K. We have interpreted the appearance of the band in terms of formation of the AuX2^--like local lattice distortion, or the bipolarons.     

Phase Diagram and Phase Separation of a Trapped Interacting Bose-Fermi Gas Mixture

In six different regimes for a spatial phase diagram of a trapped interacting Bose-Fermi gas mixture at low temperatures, we present the conditions for the spatial demixing and separation of bosons and fermions. Starting from a semiclassically thermodynamic model for the local density functional of thermal bosons and fermions,the explicit analytical expressions for the fugacities of bosons and fermions are derived in different regimes by means of a first-order perturbation method in a local-density approximation. The critical values of the fermionboson interaction strength as a function of the fractional composition of fermions have a general feature: increase,extreme and decrease with increasing the fermionic composition slightly above Bose-Einstein critical temperature.     

Copolymers at Selective Interfaces: New Bounds on the Phase Diagram

We investigate the phase diagram of disordered copolymers at the interface between two selective solvents, and in particular its weak-coupling behavior, encoded in the slope m _c of the critical line at the origin. We focus on the directed walk case, which has turned out to be, in spite of the apparent simplicity, extremely challenging. In mathematical terms, the partition function of such a model does not depend on all the details of the Markov chain that models the polymer, but only on the time elapsed between successive returns to zero and on whether the walk is in the upper or lower half plane between such returns. This observation leads to a natural generalization of the model, in terms of arbitrary laws of return times: the most interesting case being the one of return times with power law tails (with exponent 1+α, α=1/2 in the case of the symmetric random walk). The main results we present here are:

Twisted Duality Symmetry and Integrability of Hybrid Superstring on AdS2×S2

In this paper, we show that there exists a twisted duality symmetry between the Maurer-Cartan equations and the equations of motion in the hybrid formalism for the type IIB superstring in an AdS₂×S² background with Ramond-Ramond flux. As a result, from the twisted duality transformation, we construct the Lax connection with the spectral parameter, which ensures the integrability of the system.     

Translational Invariance in Phase Diagram of S = 1／2, 3／2 Spin Glass Systems

By using the replica method and the functional integral technique, the quantum XY spin glass model with ferromagnetic coupling is investigated numerically. From the numerical results of the thermodynamic and magnetic quantities we found that these quantities do not vary with the mean exchange interaction when the mean exchange interaction is lower than 1. This feature demonstrates that there are the mean interaction translational symmetries in the spin-glass and paramagnetic phases.     

Phase Diagram of the BCS–Hubbard Model in a Magnetic Field

We propose an extended BCS–Hubbard model and investigate its ground state phase diagram in an external magnetic field. By mapping the model onto a model of spinless fermions coupled with conserving Z₂ variables which are mimicked by pseudospins, the model is shown to be exactly solvable along the symmetric lines for an arbitrary on-site Hubbard interaction on the bipartite lattice. In the zero field limit, the ground states exhibit an antiferromagnetic order of pseudospins. In the lar...     

Effect of the Coadsorption of CO and O2 on the Phase Diagram of the Ziff—Gulari—Barshad Model

The effect of the coadsorption of CO and O2 on the Ziff-Gulari-Barshad surface catalytic reaction system in studied by Monte Carlo simulation.The coadsorption of both species adds an extra reaction step to the classical Ziff-Gulari-Barshad model.It is shown that the second-order phase transition from the reactive state to the O-passivated state in the Ziff-Gulari-Barshad model is eliminated,and the production rate of CO2 increases linearly along the fraction yco of CO in gas phase when it is low,in agreement with experimental results.We also find that the increase of the probability of the coadsorption leads to the decrease of the critical value of yco of the discontinuous phase transition to the CO-passivated state.     

Global Foliations of Matter Spacetimes¶with Gowdy Symmetry

A global existence theorem, with respect to a geometrically defined time, is shown for Gowdy symmetric globally hyperbolic solutions of the Einstein–Vlasov system for arbitrary (in size) initial data. The spacetimes being studied contain both matter and gravitational waves. Received: 8 December 1998 / Accepted: 20 March 1999     

Blowup of Jang’s Equation at Outermost Marginally Trapped Surfaces

The aim of this paper is to accurately describe the blowup of Jang’s equation. First, we discuss how to construct solutions that blow up at an outermost MOTS. Second, we exclude the possibility that there are extra blowup surfaces in data sets with non-positive mean curvature. Then we investigate the rate of convergence of the blowup to a cylinder near a strictly stable MOTS and show exponential convergence with an identifiable rate near a strictly stable MOTS.     

Phase Diagram Body-Centredof Catalytic Oxidation of CO on the Surface-Subsurface of a Body-Centred Cubic Structure with Eley-Rideal Process： A Monte Carlo Simulation

Monte Carlo simulation is used to explore the effects of the Eley-Rideal (ER) process on the phase diagram of the Langmuir-Hinshelwood (LH) type monomer--dimer (CO-O2) catalytic reaction on the surface and subsurface of a body-centred cubic structure, which extends to only two layers in the z-direction. The dimer (O2) is adsorbed in such a way that it takes one surface site whereas the second site is from the subsurface. For this mechanism, an interesting situation develops. The production rate of CO2 is found to be consistent with experiment. The qualitative trend of the surface oxygen coverage is not consistent with the experimental situation in one model while it is found to be consistent with that in another model, i.e. the coverage of surface oxygen decreases slowly with increase of concentration of CO (yco). Moreover, the production of CO2 can be predicted in the form of a mathematical relation.     

Thermodynamical Phase Equilibrium of Iron Nitrides at Low Temperatures

The presence of α-Fe(N),γ‘-Fe4N and ε-Fe2N1-x phases and the phase equilibrium between αFe(N) and γ′-Fe4N,and γ′-Fe4N and ε-Fe2N1-x have been studied at low temperatures below 350℃ ,according to the binary Fe-N phase diagram calculated using the sublattice-compound energy model,The α-Fe(N),γ′-Fe4N and ε-Fe2N1-x phases would be thermodynamically stable at the low temperatures.Thermodynamic phase equilibrium of the iron nitrides is supproted by the experimental results,explaining the phase formation and its stability in the Fe-N system at low temperatures.     

Promising Spectroscopic Techniques for the Portable Detection of Condensed‐Phase Contaminants on Surfaces

Abstract

Techniques for the detection of hazardous low‐volatility contaminants on surfaces are reviewed. These techniques include both point detection (i.e., in situ) and standoff detection (i.e., detection beyond the effective range of the hazard). For low‐volatility agents, a standoff distance may range from a few centimeters to hundreds of meters, depending upon physical and deposition characteristics. This survey has been restricted to optical techniques that can detect contaminants on “realistic” surfaces (including civilian and military painted surfaces) and are hand‐held or man‐portable or those techniques that are anticipated to be made hand‐held or man‐portable within 5 years to one decade.

A range of spectroscopic techniques are treated along with their requirements for power and consumables. Detection limits for these techniques are presented in the context of in‐service technologies and in the context of civilian and military toxicity/exposure limits for various chemical warfare agents. The effects of aerosols on various spectroscopic techniques are reviewed.     

The 2D Alternative Binary L—J System：Solid—Liquid Phase Diagram

The Lennard-Jones potential is introduced into the Collins model and is generalized to the two-dimensional alternative binary system.The Gibbs free energy of the binary system is calculated.According to the thermodynamic conditions of solid-liquid equilibrium,the “cigar-type ” phase diagram and the phase diagram with a minimum are obtained.The results are quite analogous to the behavior of three-dimensional substances.     

Ab Initio Study of Structural and Electronic Properties of Hexagonal BC2N

We investigate hexagonal BC2N in graphite unit cells using the first-principles method and calculate the total energies, lattice parameters, and electronic band structures after full relaxation. It is shown that stable hexagonal BC2N should be stacked sequentially with one graphite layer and one h-BN layer. The density of states indicates that this structure should have metallicity.     

The Importance of Anisotropy for Relativistic Fluids with Spherical Symmetry

It is shown that an effective anisotropic spherically symmetric fluid model with heat flow can absorb the addition to a perfect fluid of pressure anisotropy, heat flow, bulk and shear viscosity, electric field and null fluid. In most cases the induction of effective heat flow can be avoided.     

Scalar Field at the Phase Transition Point of RNdS Space

The real scalar field equation between the outer black hole horizon and the cosmological horizon is solved in the Reissner-Nordstroem-de Sitter space when it is at the phase transition point. We use an accurate approximation,the polynomial approximation, to approximate the tortoise coordinate x(r) for obtaining the inverse function r=r(x) and then for solving the wave equation. The case where the two horizons are very close to each other is discussed in detail. It is found that the wave function is characteristically similar to the harmonic in the whole range with x as the independent coordinate, while the waves pile up near the horizons with r as the independent coordinate. Furthermore, we find that the height of the potential increases as the cosmological constant A decreases.     

Light-Front Quantization of the Chern–Simons–Higgs Theory in the Broken Symmetry Phase

Two-space one-time dimensional Chern–Simons–Higgs theory is quantized on the light-front in the broken (frozen) symmetry phase of the Higgs potential.     

Phase Diagram of Quantum Chromodynamics in the Temperature–Baryon Density–Magnetic Field Parameter Space

Physics of Atomic Nuclei - The phase diagram of quantum chromodynamics under different external parameters, such as the temperature, baryon chemical potential, and magnetic field strength, is...     

Unified Symmetry of Nonholonomic Mechanical Systems of Non-Chetaev‘s Type with Unilateral Constraints

The definition and the criterion for a unified symmetry of nonholonomic mechanical systems of nonChetaev‘s type with unilateral constraints are presented based on the total time derivative along the trajectory of the system. A new conserved quantity, as well as the Noether conserved quantity and the Hojman conserved quantity,jeduced from the unified symmetry, is obtained. An example is given to illustrate the application of the results.