Qiuping A. Wang

On the generalized entropy pseudoadditivity for complex systems

We show that Abes general pseudoadditivity for entropy prescribed by thermal equilibrium in nonextensive systems holds not only for entropy, but also for energy. The application of this general pseudoadditivity to Tsallis entropy tells us that the factorization of the probability of a composite system into a product of the probabilities of the subsystems is just a consequence of the existence of thermal equilibrium and not due to the independence of the subsystems.

NONEXTENSIVE BLACK-BODY DISTRIBUTION FUNCTION AND EINSTEIN'S COEFFICIENTS A AND B

Abstract The nonextensive statistics of a boson gas within the dilute gas approximation is applied to black-body radiation. Einsteins spontaneous emission coefficient A21, stimulated emission coefficient B21, and absorption coefficient B12 are studied in connection with this new statistical mechanics. Relations including nonextensivity between these coefficients are obtained.

Extensive form of equilibrium nonextensive statistics

It is argued that, in nonextensive statistical mechanics with Tsallis entropy, the factorization of compound probability over subsystems is a consequence of the existence of thermodynamic equilibrium in the composite system and should be respected by all exact calculations concerning equilibrium subsystems. Using nonadditive energy satisfying this factorization, we propose an additive formalism of nonextensive statistical mechanics with additive q-deformed physical quantities and exponential distributions. This formalism leads to exact quantum gas distributions different from those given by factorization approximation with additive energy. The fermion distribution of the present work shows similar characteristics to the distribution of strongly correlated electrons given by numerical analysis with the Kondo t-J model.

Unnormalized nonextensive expectation value and zeroth law of thermodynamics

Abstract On the basis of complete distribution normalization Tr ρ =1 and unnormalized average energy E= Tr ρ q H , we show an attempt to establish the zeroth law of thermodynamics within the framework of nonextensive statistical mechanics for canonical ensemble. The first law of thermodynamics and the statistical interpretation of heat and work are discussed.

Generalized blackbody distribution within the dilute gas approximation

We consider the application of Tsallis’ generalized statistical mechanics to systems of quantum particles (fermions or bosons). An approach due to Buyukkilic et al. to find analytic formulae for quantum distribution functions and its application to generalized blackbody radiation is discussed. Generalized blackbody laws (Stefan–Boltzmann law, Rayleigh–Jeans law and Wien empirical distribution law) are proposed.

Possible canonical distributions for finite systems with nonadditive energy

It is shown that a small system in thermodynamic equilibrium with a finite thermostat can have a q-exponential probability distribution which closely depends on the energy nonextensivity and the particle number of the thermostat. The distribution function will reduce to the exponential one at the thermodynamic limit. However, the nonextensivity of the system should not be neglected.

Nonextensive boson gas and specific heat of 4He superfluid

The temperature dependence of the heat capacity Cv of the boson gas is studied within the generalized quantum statistics. The generalized heat capacity (Cv)q is shown to increase strongly at all temperatures with increasing nonextensive parameter q. This (Cv)q behavior is used to reproduce the observed curve of Cv(T) of the liquid 4He(II) for the temperature range 1K⩽T⩽2.17K with particular q values. We obtain an almost linear T-dependence of parameter q which increases with increasing temperature from q≈0.5 at 1K to q≈1.35 at 2.17K. The observed 4He(I)−4He(II) transition temperature (2.17K) is also reproduced with q≈1.36.

Ab initio investigation of the lattice dynamics of fluoride scheelite LiYF4

We report on the phonon dynamics of LiYF4 obtained by a direct method using density functional theory. The longitudinal optical/transverse optical (LO/TO) splitting was not investigated. First, the equilibrium structure was evaluated via a full relaxation of the structure. Then phonon dispersion curves, velocities of sound, frequencies of Raman and infrared active modes, and density of states were calculated. Moreover, the elastic stiffness coefficients and specific heat capacity were evaluated from these data. The agreement between calculated and experimental frequencies are acceptable since, in general, the discrepancies are within 8%.