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91.
We study the phase diagram ofS=1 antiferromagnetic chains with particular emphasis on the Haldane phase. The hidden symmetry breaking measured by the string order parameter of den Nijs and Rommelse can be transformed into an explicit breaking of aZ
2×Z
2 symmetry by a nonlocal unitary transformation of the chain. For a particular class of Hamiltonians which includes the usual Heisenberg Hamiltonian, we prove that the usual Néel order parameter is always less than or equal to the string order parameter. We give a general treatment of rigorous perturbation theory for the ground state of quantum spin systems which are small perturbations of diagonal Hamiltonians. We then extend this rigorous perturbation theory to a class of diagonally dominant Hamiltonians. Using this theory we prove the existence of the Haldane phase in an open subset of the parameter space of a particular class of Hamiltonians by showing that the string order parameter does not vanish and the hiddenZ
2×Z
2 symmetry is completely broken. While this open subset does not include the usual Heisenberg Hamiltonian, it does include models other than VBS models. 相似文献
92.
Teruhisa S. Komatsu Naoko Nakagawa Shin-Ichi Sasa Hal Tasaki 《Journal of statistical physics》2009,134(2):401-423
Recently a novel concise representation of the probability distribution of heat conducting nonequilibrium steady states was
derived. The representation is valid to the second order in the “degree of nonequilibrium”, and has a very suggestive form
where the effective Hamiltonian is determined by the excess entropy production. Here we extend the representation to a wide
class of nonequilibrium steady states realized in classical mechanical systems where baths (reservoirs) are also defined in
terms of deterministic mechanics. The present extension covers such nonequilibrium steady states with a heat conduction, with
particle flow (maintained either by external field or by particle reservoirs), and under an oscillating external field. We
also simplify the derivation and discuss the corresponding representation to the full order. 相似文献
93.
Kiiti Siratori Tamotsu Kondow Akira Tasaki 《Journal of Physics and Chemistry of Solids》1978,39(3):225-232
The magnetic susceptibilities (χ) of quinolinium·(TCNQ)2, N-methyl phenazinium·TCNQ and Li·TCNQ were measured from 2 to 300 K and are discussed in connection with the low-temperature specific heats (C) measured by other authors, χ is decomposed into three parts: χd the temperature-independent part, χc, Curie-Weiss type paramagnetism, and χp, the remainder. Correspondingly, C is composed of three terms, γT, H/T2 and αT3. The electronic state of these substances is discussed in terms of each type of susceptibility.The model, on which the above separation of χ and C is based, defines two types of electrons: localized electrons associated with a magnetic moment and band electrons. Though this model is useful phenomenologically, it is shown that the analysis of χ on the basis of this model indicates less band electrons and more localized electrons or stronger magnetic interactions than does that of C. 相似文献
94.
H. Tasaki 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,64(3-4):365-372
It is believed that strong ferromagnetic orders in some solids are generated by subtle interplay between quantum many-body effects and spin-independent Coulomb interactions between electrons. Here we describe our rigorous and constructive approach to ferromagnetism in the Hubbard model, which is a standard idealized model for strongly interacting electrons in a solid. 相似文献
95.
For a previously introduced conservative multibaker map with energy, the Gaspard–Gilbert–Dorfman entropy production of the stationary state induced by the flux boundary condition is calculated and the entropy production is shown (i) to be nonnegative, (ii) to vanish in the fine-grained limit for finite chains, (iii) to take the phenomenologically expected value in the middle of the chain and to deviate from it near the boundaries, and (iv) to reduce to the phenomenological expression in the scaling limit where the lattice site nZ and time tZ are scaled respectively as n=L
X and t=L
T and the limits of L
+ and L
+ are taken while keeping the diffusion coefficient D=lL
/L
2
constant, l being the transition rate of the model. The mass and heat transports are also studied in the scaling limit under an additional assumption that the edges of the chain are in equilibrium with different temperatures. In the linear heat transport regime, Fourier's law of heat conduction and the thermodynamic expression of the associated entropy production are obtained. 相似文献
96.
Starting from and only using classical Hamiltonian dynamics, we prove the maximum work principle in a system where macroscopic
dynamical degrees of freedom are intrinsically coupled to microscopic degrees of freedom. Unlike in many of the standard and
recent works on the second law, the macroscopic dynamics is not governed by an external action but undergoes the back reaction
of the microscopic degrees of freedom. Our theorems cover such physical situations as impact between macroscopic bodies, thermodynamic
machines, and molecular motors. Our work identifies and quantifies the physical limitations on the applicability of the second
law for small systems.
相似文献
97.
We analyze some solvable models of a quantum mechanical system in interaction with a reservoir when the initial state is not factorized. We apply Nakajima-Zwanzig’s projection method by choosing a reference state of the reservoir endowed with the mixing property. In van Hove’s limit, the dynamics is described in terms of a master equation. We observe that Markovianity becomes a valid approximation for timescales that depend both on the form factors of the interaction and on the observables of the reservoir that can be measured. 相似文献
98.