Microscopic description in the Gaussian approximation of the nematic-isotropic phase transition

1991 ◽  
Vol 69 (2) ◽  
pp. 154-160
Author(s):  
P. A. Pashkov ◽  
S. I. Vasiliev
Keyword(s):  
Field Theory ◽  
Phase Transition ◽  
Gaussian Approximation ◽  
Dimensional Space ◽  
Mean Field Theory ◽  
Mean Field ◽  
Isotropic Phase ◽  
Cluster Approximation ◽  
Field Fluctuations ◽  
The Mean

The nematic-isotropic phase transition of a system of nonpolar rodlike molecules is considered. The mean-field theory is extended to take into account the local field fluctuations in the Gaussian approximation. The calculations are performed in the five-dimensional space of the order-parameter components. The numerical results are obtained for the lattice system of molecules and compared with the calculations in the mean-field theory, cluster approximation, and Monte-Carlo simulation data.

scholarly journals Modeling the Magnetocaloric Effect of Nd0.67Ba0.33Mn0.98 Fe0.02O3 by the Mean Field Theory

2020 ◽  
Author(s):  
Mohamed Hsini ◽  
Sadok Zemni
Keyword(s):  
Field Theory ◽  
Phase Transition ◽  
Magnetic Properties ◽  
Magnetic Fields ◽  
Magnetocaloric Effect ◽  
Mean Field Theory ◽  
Mean Field ◽  
Entropy Change ◽  
Magnetization Curves ◽  
The Mean

In this paper, we have exploited the mean field theory combined with the Bean-Rodbell model to justify the magnetocaloric effect (MCE) in Nd0.67Ba0.33Mn0.98Fe0.02O3 sample. The simulation of some magnetic properties has been investigated. Modeling magnetization curves have been successfully achieved using this model. The second-order ferromagnetic-paramagnetic (FM-PM) phase transition of our system has been verified through the value of the parameter which controls the transition nature in the Bean-Rodbell model. Theoretical and experimental expressions, which have rated the magnetic entropy change ( − ∆ S M ) under various magnetic fields, have been derived. Theoretical ( − ∆ S M ) curves have been compared to the experimental ones.

scholarly journals Nematic-isotropic phase transition: An extended mean field theory

1993 ◽  
Vol 70 (9) ◽  
pp. 1271-1274 ◽  
Author(s):  
Ruibao Tao ◽  
Ping Sheng ◽  
Z. F. Lin
Keyword(s):  
Field Theory ◽  
Phase Transition ◽  
Mean Field Theory ◽  
Mean Field ◽  
Isotropic Phase

scholarly journals Evidence of exactness of the mean-field theory in the nonextensive regime of long-range classical spin models

2000 ◽  
Vol 61 (17) ◽  
pp. 11521-11528 ◽  
Author(s):  
Sergio A. Cannas ◽  
A. C. N. de Magalhães ◽  
Francisco A. Tamarit
Keyword(s):  
Field Theory ◽  
Long Range ◽  
Mean Field Theory ◽  
Mean Field ◽  
Spin Models ◽  
Classical Spin ◽  
The Mean ◽  
Classical Spin Models
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