Investigation of surface energies in spin crossover nanomaterials: the role of surface relaxations

2017 ◽  
Vol 19 (19) ◽  
pp. 12276-12281 ◽  
Author(s):  
Mirko Mikolasek ◽  
William Nicolazzi ◽  
Férial Terki ◽  
Gábor Molnár ◽  
Azzedine Bousseksou
Keyword(s):  
Spin Crossover ◽  
Spin Transition ◽  
Mean Field ◽  
Transition Phenomenon ◽  
Field Approach ◽  
Surface Energies

We analyse in detail the role of surface relaxations on the spin transition phenomenon through an Ising-like model solved in the inhomogeneous mean field approach.

scholarly journals Paradox of integration — mean field approach

2017 ◽  
Vol 28 (11) ◽  
pp. 1750133 ◽  
Author(s):  
Krzysztof Kułakowski ◽  
Piotr Gronek ◽  
Alfio Borzì
Keyword(s):  
Social Status ◽  
Positive Emotions ◽  
Mean Field ◽  
Computational Approach ◽  
Transient Time ◽  
Field Approach ◽  
The Social ◽  
The Mean ◽  
High Social Status

Recently, a computational model has been proposed of the social integration, as described in sociological terms by Blau. In this model, actors praise or critique each other, and these actions influence their social status and raise negative or positive emotions. The role of a self-deprecating strategy of actors with high social status has also been discussed there. Here, we develop a mean field approach, where the active and passive roles (praising and being praised, etc.) are decoupled. The phase transition from friendly to hostile emotions has been reproduced, similarly to the previously applied purely computational approach. For both phases, we investigate the time dependence of the distribution of social status. There we observe a diffusive spread, which — after some transient time — appears to be limited from below or from above, depending on the phase. As a consequence, the mean status flows.

scholarly journals Unconventional phase transitions in strongly anisotropic 2D (pseudo)spin systems

2018 ◽  
Vol 185 ◽  
pp. 08006
Author(s):  
Vitaly Konev ◽  
Evgeny Vasinovich ◽  
Vasily Ulitko ◽  
Yury Panov ◽  
Alexander Moskvin
Keyword(s):  
Magnetic Field ◽  
Monte Carlo ◽  
Phase Transitions ◽  
Ground State ◽  
Quantum Monte Carlo ◽  
Mean Field ◽  
Spin Systems ◽  
Field Approach ◽  
Generalized Mean

We have applied a generalized mean-field approach and quantum Monte-Carlo technique for the model 2D S = 1 (pseudo)spin system to find the ground state phase with its evolution under application of the (pseudo)magnetic field. The comparison of the two methods allows us to clearly demonstrate the role of quantum effects. Special attention is given to the role played by an effective single-ion anisotropy ("on-site correlation").

Dynamical model for spin-crossover solids. II. Static and dynamic effects of light in the mean-field approach

2000 ◽  
Vol 62 (22) ◽  
pp. 14806-14817 ◽  
Author(s):  
Kamel Boukheddaden ◽  
Isidor Shteto ◽  
Benoit Hôo ◽  
François Varret
Keyword(s):  
Spin Crossover ◽  
Mean Field ◽  
Dynamical Model ◽  
Dynamic Effects ◽  
Field Approach ◽  
The Mean

scholarly journals Non-linear and chaotic dynamo regimes

2012 ◽  
Vol 8 (S294) ◽  
pp. 387-398
Author(s):  
Axel Brandenburg
Keyword(s):  
Mean Field ◽  
Rotation Frequency ◽  
Magnetic Activity ◽  
Current Status ◽  
Small Scale ◽  
Field Approach ◽  
Magnetic Prandtl Number ◽  
The Mean ◽  
Open Question

AbstractAn update is given on the current status of solar and stellar dynamos. At present, it is still unclear why stellar cycle frequencies increase with rotation frequency in such a way that their ratio increases with stellar activity. The small-scale dynamo is expected to operate in spite of a small value of the magnetic Prandtl number in stars. Whether or not the global magnetic activity in stars is a shallow or deeply rooted phenomenon is another open question. Progress in demonstrating the presence and importance of magnetic helicity fluxes in dynamos is briefly reviewed, and finally the role of nonlocality is emphasized in modeling stellar dynamos using the mean-field approach. On the other hand, direct numerical simulations have now come to the point where the models show solar-like equatorward migration that can be compared with observations and that need to be understood theoretically.

Comparison of static and light-induced thermal hystereses of a spin-crossover solid, in a mean-field approach†

2001 ◽  
Vol 13 (11) ◽  
pp. 2481-2495 ◽  
Author(s):  
Cristian Enachescu ◽  
Jorge Linarès ◽  
François Varret
Keyword(s):  
Spin Crossover ◽  
Mean Field ◽  
Field Approach

Photo-induced spin-transition: the role of the iron(II) environment distortion

2005 ◽  
Vol 61 (1) ◽  
pp. 25-28 ◽  
Author(s):  
Mathieu Marchivie ◽  
Philippe Guionneau ◽  
Jean-François Létard ◽  
Daniel Chasseau
Keyword(s):  
Spin Crossover ◽  
Strong Dependence ◽  
Spin Transition ◽  
Magnetic Behaviour ◽  
Magnetic Data ◽  
Structural Parameter ◽  
Structure Property ◽  
Wide Range ◽  
Shed Light

The [FeL n (NCS)2] iron(II) spin-crossover complexes cover a wide range of magnetic behaviour. Owing to the large number of known structural and magnetic data, this series is perfectly adapted to the investigation of the structure–magnetic properties relationship. In this paper we propose a new structural parameter, denoted Θ, which is used to correlate the features of the spin-crossover phenomena with the distortion of the iron environment. In particular, this parameter has shed light on the role of such distortion on the limiting temperature of photo-inscription, known as T(LIESST). A strong dependence of T(LIESST) on Θ is clearly demonstrated. The stronger the distortion the higher the T(LIESST) value. This structure–property dependence represents, for instance, a powerful tool to estimate the highest potential T(LIESST) value for a series of complexes. This limit in the [FeL n (NCS)2] series is estimated to be around 120 K, which probably prevents their use in any industrial application.

NUCLEAR FISSION WITHIN THE MEAN-FIELD APPROACH

2009 ◽  
Vol 18 (04) ◽  
pp. 798-807 ◽  
Author(s):  
J. SKALSKI
Keyword(s):  
Simple Model ◽  
Density Matrix ◽  
Hermitian Operator ◽  
Mean Field ◽  
Nuclear Fission ◽  
Decay Rates ◽  
Instanton Action ◽  
Field Approach ◽  
The Mean

We discuss the mean-field instanton method for calculating decay rates of the sponteneous fission. Based on our recent work, we stress the role of the velocity-momentum relations which make the instanton action minimal, and the choice of a time-even density matrix and a time-odd hermitian operator as special variables making the adiabatic limit transparent. We also present an analytic study of a simple model of barrier tunneling, which illustrates the importance of the velocity-momentum constraints.

Dynamical model for spin-crossover solids. I. Relaxation effects in the mean-field approach

2000 ◽  
Vol 62 (22) ◽  
pp. 14796-14805 ◽  
Author(s):  
Kamel Boukheddaden ◽  
Isidor Shteto ◽  
Benoit Hôo ◽  
François Varret
Keyword(s):  
Spin Crossover ◽  
Mean Field ◽  
Dynamical Model ◽  
Field Approach ◽  
Relaxation Effects ◽  
The Mean
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