scholarly journals Approach to equilibrium via Tsallis distributions in a realistic ionic-crystal model and in the FPU model

2020 ◽  
Vol 229 (5) ◽  
pp. 743-749
Author(s):  
Andrea Carati ◽  
Luigi Galgani ◽  
Fabrizio Gangemi ◽  
Roberto Gangemi
Keyword(s):  
Ionic Crystal ◽  
Approach To Equilibrium ◽  
Crystal Model

Thermal fluctuations in a realistic ionic-crystal model

2022 ◽  
Vol 586 ◽  
pp. 126463
Author(s):  
Fabrizio Gangemi ◽  
Roberto Gangemi ◽  
Andrea Carati ◽  
Luigi Galgani
Keyword(s):  
Ionic Crystal ◽  
Thermal Fluctuations ◽  
Crystal Model

Is Y1Ba2Cu3O7 stiff or soft?

1990 ◽  
Vol 5 (2) ◽  
pp. 241-244 ◽  
Author(s):  
Hassel Ledbetter ◽  
Ming Lei
Keyword(s):  
High Pressure ◽  
Metal Oxide ◽  
Physical Properties ◽  
Bulk Modulus ◽  
Model Calculation ◽  
Ionic Crystal ◽  
Oxide Superconductor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystal Model

Using several measured and calculated physical properties, we argue that the high-Tc metal-oxide superconductor Y1Ba2Cu3O7 is elastically soft compared with BaTiO3 or SrTiO3. We conclude that the bulk modulus equals approximately 107 GPa, despite several high-pressure x-ray diffraction studies that report values up to approximately 200 GPa. Part of the argument uses an ionic-crystal-model calculation of the bulk modulus.

Elastic constants of polycrystalline Y1Ba2Cu3Ox

1992 ◽  
Vol 7 (11) ◽  
pp. 2905-2907 ◽  
Author(s):  
Hassel Ledbetter
Keyword(s):  
Grain Boundary ◽  
Bulk Modulus ◽  
Debye Temperature ◽  
Oxygen Content ◽  
Elastic Constants ◽  
Model Prediction ◽  
Ionic Crystal ◽  
Poisson Ratio ◽  
Young’S Moduli ◽  
Crystal Model

We measured the elastic constants of polycrystalline Y1Ba2Cu3Ox with eleven oxygen contents varying from 6.2 to 6.9. Reported properties include sound velocities; bulk, shear, Young's moduli; Poisson ratio; Debye temperature. After correction to the void-free state, the measurements fail to show a systematic dependence on oxygen content. Focusing on the bulk modulus, all measurements fall below an ionic-crystal model prediction, by 5–50%. We attribute this macroscopic softness to either microcracks or weak grain-boundary mechanical linkages. For the case x = 6.9, we suggest a set of intrinsic elastic constants.

Critical TemperaturesTcof Ionic-Crystal Model for Infinite-Layer Compounds

1992 ◽  
Vol 61 (12) ◽  
pp. 4663-4664 ◽  
Author(s):  
Chikao Kawabata ◽  
Takamitsu Nakanishi
Keyword(s):  
Ionic Crystal ◽  
Infinite Layer ◽  
Crystal Model

The Nonempirical Calculation of the Cation Ordering and Lattice Dynamics in the Solid Solutions of PbSc1/2Nb1/2O3 and PbSc1/2Ta1/2O3

2006 ◽  
Vol 115 ◽  
pp. 305-310
Author(s):  
V.I. Zinenko ◽  
S.N. Sofronova
Keyword(s):  
Solid Solutions ◽  
Ionic Crystal ◽  
Mean Field ◽  
Nonempirical Calculation ◽  
Cation Ordering ◽  
Effective Hamiltonian ◽  
The Monte Carlo Method ◽  
Ordered Phases ◽  
Phase Transition Temperatures ◽  
Crystal Model

An effective Hamiltonian for the study of Sc–Nb(Ta) cation ordering in PbSc1/2Nb(Ta)1/2O3 solid solutions is worked out. To determine the parameters of the effective Hamiltonian, a nonempirical calculation is performed within an ionic-crystal model taking into account the deformation, dipole, and quadrupole polarizabilities of ions. The phase transition temperatures are calculated by the mean field, the cluster approximations, and the Monte-Carlo method. Within the same ionic-crystal model, we calculated the high-frequency permittivity, Born dynamic charges, and the phonon spectrum for completely disordered and ordered phases.

Exact solution of a four-site crystal model for an intermediate-valence system

1986 ◽  
Vol 47 (6) ◽  
pp. 1029-1034 ◽  
Author(s):  
J.C. Parlebas ◽  
R.H. Victora ◽  
L.M. Falicov
Keyword(s):  
Exact Solution ◽  
Intermediate Valence ◽  
Crystal Model

Approach to Equilibrium, the H-Theorem and Irreversibility

2018 ◽  
Author(s):  
Sauro Succi
Keyword(s):  
Boltzmann Equation ◽  
Detailed Knowledge ◽  
Approach To Equilibrium ◽  
The Boltzmann Equation ◽  
H Theorem ◽  
Irreversible Evolution

Like most of the greatest equations in science, the Boltzmann equation is not only beautiful but also generous. Indeed, it delivers a great deal of information without imposing a detailed knowledge of its solutions. In fact, Boltzmann himself derived most if not all of his main results without ever showing that his equation did admit rigorous solutions. This Chapter illustrates one of the most profound contributions of Boltzmann, namely the famous H-theorem, providing the first quantitative bridge between the irreversible evolution of the macroscopic world and the reversible laws of the underlying microdynamics.

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