Quasiparticle model

Massidda S, Continenza A, Posternak M and Baldereschi A 1997 Quasiparticle energy bands of transition-metal oxides within a model GW scheme Phys. Rev. B 55 13 494-502... 

This idea that the heat was transfered by a random walk was used early on by Einstein [21] to calculate the thermal conductance of crystals, but, of course, he obtained numbers much lower than those measured in the experiment. As we now know, crystals at low enough T support well-defined quasiparticles—the phonons—which happen to carry heat at these temperatures. Ironically, Einstein never tried his model on the amorphous solids, where it would be applicable in the / fp/X I regime. 

Straightforward analytical models, however, receive particular attention in the present book, as they are of unique significance in the comprehension of physical phenomena and, moreover, provide the very language to describe them. To exemplify, recall the effect caused on the phase transition theory by the exactly soluble two-dimensional Ising model. Nor can one overestimate the role of the quasiparticle concept in the theory of electronic and vibrational excitations in crystals. As new experimental evidence becomes available, a simplistic physical picture gets complicated until a novel organizing concept is created which covers the facts known from the unified standpoint (thus underlying the aesthetic appeal of science). 

Silicon is a model for the fundamental electronic and mechanical properties of Group IV crystals and the basic material for electronic device technology. Coherent optical phonons in Si revealed the ultrafast formation of renormalized quasiparticles in time-frequency space [47]. The anisotropic transient reflectivity of n-doped Si(001) featured the coherent optical phonon oscillation with a frequency of 15.3 THz, when the [110] crystalline axis was parallel to the pump polarization (Fig. 2.11). Rotation of the sample by 45° led to disappearance of the coherent oscillation, which confirmed the ISRS generation,... 

Landau-Fermi liquid, 23 840 Landau quasiparticle model, 23 840 Land cost, 9 527 Landering, 8 438-439 Land-farming, 3 768 defined, 3 759t Landfill gas, 25 880 Landfill leachate treatment, reverse osmosis in, 21 646-647 Landfill liners, 25 877-878... 

Abstract We review our quasiparticle model for the thermodynamics of strongly interacting matter at high temperature, and its extrapolation to non-zero chemical potential. Some implications of the resulting soft equation of state of quark matter at low temperatures are pointed out. 

In the following we will outline a thermodynamical quasiparticle model, which can be derived in a series of approximations. 

HTL quasiparticle model. In QCD, the truncation of a resummation scheme based on 2-point functions is delicate because of gauge invariance. 

Phenomenological quasiparticle model. Taking into account only the dominant contributions in (7), namely the quasiparticle contributions of the transverse gluons as well as the quark particle-excitations for Nj / 0, we arrive at the quasiparticle model [8], The dispersion relations can be even further simplified by their form at hard momenta, u2 h2 -rnf, where m.t gT are the asymptotic masses. With this approximation of the self-energies, the pressure reads in analogy to the scalar case... 

The phenomenological quasiparticle model can be generalized to non-zero chemical potential, where the quasiparticle masses of the gluons and quarks read... 

Finally, as a direct confirmation of our mapping procedure, the quasiparticle model can also successfully describe the available lattice data for p(g. T) with... 

Figure 5. The quark number susceptibility for Nf = 2, calculated from the quasiparticle model with the same parameters as in Figs. 3 and 4, for several chemical potentials compared to the lattice data [14] at /u = 0.

At this time, the fastest growing area in the field of nanophysics is in the studies of buckyballs and nanotubes. After the discovery [33] of the Qo molecule, many properties of the molecule and solids formed from the molecule were explored. The doped C6o crystals showed interesting behavior, including superconductivity. [34] The standard model, including the GW quasiparticle theory, was used [35] successfully to explore the energy band structure, and the superconducting properties appear to be consistent with the BCS theory. [36]... 

In conclusion, we mention that the effects of disorder on the kinetics of quasiparticles confined in an insulator/normal-metal/superconductor (INS) hybrid structure due to Andreev reflections was first considered in Ref. [12] within a model where the disorder is provided by irregularities on the I/N boundary through the normal scattering of quasiparticles. 

It was shown then that all these observed features can be described self-consistently by Fermi-liquid model for quasiparticles in clean d-wave superconductor with resonant intralayer scattering [14]. The superconducting gap is expressed as A([Pg.185]

Fig. 10b shows a comparison of our data with the microwave results [18]. The origin of the peak of oab(T) has been widely discussed as a result of a d-wave symmetry of the OP in BSCCO and YBCO. In particular, in a d-wave Fermi-liquid model it was shown that at low temperatures oab grows with temperature as [27] o(m—>0,T) = <70o (1 + fl2), where Ooo is a universal inplane conductivity introduced by Lee [28], Ooo = n e2 /(n mabAo) with mab the effective quasiparticle in-plane mass. 

Level schemes of Sm-138, Sm-136, Sm-134 and Nd- 132 are given in fig. 4 and the lifetimes of some excited states are summarized in table 1. The excitation energies in these nuclei have been computed on the basis of the interacting boson model, IBM-2 0TS78J. The computations are in good agreement with the experimental results of Sm-136, Sm-134 and Nd-132 but not of Sm-138. The extended IBM-2 which includes the interaction between the bosons and a two-quasiparticle 10+ state can reproduce the experimental situation ... 

A number of experiments, shown in Fig.l, were used to determine the value of the energy gap parameter and its temperature dependence according to the modified model of Blonder, Tinkham, and Klapwijk [22]. This model takes into consideration the finite lifetime of quasiparticles as a result of inelastic scattering processes. In this way we got a value A0 - 3 meV which is close to from the value 3.4 meV found in NbsSn [23]. The BCS model describes quite well the dependence A(T) (Fig.2) obtained from the experimental results. 

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