scholarly journals Optical Conductivity on Charge Order Transition in Organic Dirac Electron System α-(BEDT-TTF)2I3

2018 ◽  
Author(s):  
Daigo Ohki ◽  
Genki Matsuno ◽  
Yukiko Omori ◽  
Akito Kobayashi
Keyword(s):  
Optical Conductivity ◽  
Mean Field Theory ◽  
Mean Field ◽  
Charge Order ◽  
Electron System ◽  
Order Transition ◽  
Peak Structure ◽  
Dirac Electron ◽  
The Mean ◽  
Valence Bands

The optical conductivity in the charge order phase is calculated in the extended Hubbard model describing an organic Dirac electron system α-(BEDT-TTF)2I3 using the mean field theory and the Nakano-Kubo formula. A peak structure due to interband excitation being characteristic in two-dimensional Dirac electron system is found above the charge order gap. It is shown that the peak structure originates from the Van Hove singularities of the conduction and valence bands, where those singularities are located at a saddle point between two Dirac cones in momentum space. The frequency of the peak structure exhibits drastic change in the vicinity of the charge order transition.

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

scholarly journals RELATIVE MOTION CORRECTION TO FISSION BARRIERS

2008 ◽  
Vol 17 (01) ◽  
pp. 151-159 ◽  
Author(s):  
J. SKALSKI
Keyword(s):  
Relative Motion ◽  
Cluster Model ◽  
Motion Correction ◽  
Mean Field Theory ◽  
Mean Field ◽  
Ternary Fission ◽  
Skyrme Interaction ◽  
Hartree Fock ◽  
Fission Barriers ◽  
The Mean

We discuss the effect of kinetic energy of the relative motion becoming spurious for separate fragments on the selfconsistent mean-field fission barriers. The treatment of the relative motion in the cluster model is contrasted with the necessity of a simpler and approximate approach in the mean-field theory. A scheme of the energy correction to the Hartree-Fock is proposed. The results obtained with the effective Skyrme interaction SLy 6 show that the correction, previously estimated as ~ 8 MeV in A = 70 - 100 nuclei, amounts to 4 MeV in the medium heavy nucleus 198 Hg and to null in 238 U . However, the corrected barrier implies a shorter fission half-life of the latter nucleus. The same effect is expected to lower barriers for multipartition (i.e. ternary fission, etc) and make hyperdeformed minima less stable.

MODIFIED VAN DER WAALS MODEL FOR SURFACE-MELTING DISCUSSION

1995 ◽  
Vol 02 (06) ◽  
pp. 773-785 ◽  
Author(s):  
L. WOJTCZAK ◽  
J.H. RUTKOWSKI
Keyword(s):  
Thermodynamic Potential ◽  
Van Der Waals ◽  
Mean Field Theory ◽  
Mean Field ◽  
Energy Functional ◽  
Surface Melting ◽  
Free Energy Functional ◽  
Thickness Profile ◽  
The Mean ◽  
Surface Liquid

The thermodynamic potential governing the surface-melting, considered in terms of the crystallinity and its profile is related to the Gibbs free-energy functional, leads to van der Waals equation of state. The presented construction allows us to determine the mean-field coefficients by their reference to material constants. The model is applied to the surface-melting discussion within the Landau-type mean-field theory of phase-transitions. In particular, the surface-melting temperature is estimated and temperature dependence of the surface liquid-like layer thickness profile is obtained.

On the mean-field theory of spin glasses

1980 ◽  
Vol 13 (3) ◽  
pp. 403-418 ◽  
Author(s):  
A Blandin ◽  
M Gabay ◽  
T Garel
Keyword(s):  
Field Theory ◽  
Spin Glasses ◽  
Mean Field Theory ◽  
Mean Field ◽  
The Mean
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