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Nonequilibrium Reduced-Density Operator for Nanoscopic Systems

100%
Jacyna-Onyszkiewicz Z.
Acta Physica Polonica A
|
2002
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vol. 102
|
issue 6
717-727
EN
Retarded forms of the nonequilibrium reduced-density operator are derived from the generalized Schrödinger variational principle of a system with both mechanical and thermal perturbations, taking into account the additional condition that the values of generalized thermodynamic coordinates are fixed at infinitely remote past. This reduced density operator may be useful in describing nonequilibrium properties of nanoscopic and mesoscopic systems, as well as ultrathin films. With the help of this reduced-density operator the generalized Green-Kubo formulae are obtained.
2
Content available remote

Generalised Equilibrium Reduced-Density Operator

100%
Jacyna-Onyszkiewicz Z.
Acta Physica Polonica A
|
2018
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vol. 133
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issue 5
1231-1240
EN
Equilibrium reduced-density operators for subsystems of the universe are derived from the generalised Schrödinger variational principle, additionally assuming that the values of von Neumann entropy for the subsystems are fixed and higher than zero. The obtained reduced-density operator may be useful for description of the properties of an arbitrary system (macroscopic, mesoscopic, nanoscopic, or microscopic) in the equilibrium mixed state.
3
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Spatial Dependence of Magnetization and Gaussian Fluctuations of Molecular Field in an Ising Nanopyramid Interacting with the Substrate

63%
Borkowski L., Jacyna-Onyszkiewicz Z.
Acta Physica Polonica A
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2009
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vol. 115
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issue 1
375-377
EN
We study thermodynamic properties of an Ising model of a ferromagnetic nanoscopic pyramid deposited on a ferromagnetic bulk substrate. The influence of the interaction between the pyramid and the substrate is calculated in terms of the reduced-state (density) operator used for description of thermodynamic properties of nanoscopic systems. The spatial distribution of magnetization in the nanopyramid is obtained in the Gaussian fluctuations approximation.
4
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Gaussian Fluctuations of Two Molecular Fields in the Blume-Emery-Griffiths Model

63%
Jaworski W., Jacyna-Onyszkiewicz Z.
Acta Physica Polonica A
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2011
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vol. 119
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issue 6
846-849
EN
The Blume-Emery-Griffiths model for spins S=1 in a bilayer with z=5 nearest neighbours is studied with the use of Gaussian fluctuations approximation. The fluctuations of two molecular fields, connected with two order parameters, are introduced. Their influence on phase diagrams for non-negative values of the biquadratic coupling constant is taken under consideration. The results are compared with those obtained by the mean-field approximation and discussed.
5
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Spatial Distribution of Magnetization in the Pyramid-Like Ising Nanoscopic System Interacting with the Substrate

63%
Borkowski L., Jacyna-Onyszkiewicz Z.
Acta Physica Polonica A
|
2007
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vol. 112
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issue 6
1223-1230
EN
We study thermodynamic properties of an Ising model of a ferromagnetic nanoscopic pyramid deposited onto a ferromagnetic bulk substrate. The influence of the interaction between the pyramid and the substrateis calculated in terms of the reduced-state (density) operator used for description of thermodynamic properties of nanoscopic systems. The spatial distribution of the magnetization in the nanoscopic pyramid is obtained in the molecular field approximation.
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