scholarly journals Free energy of a charged oscillator in a magnetic field and coupled to a heat bath through momentum variables

2013 ◽  
Vol 2013 (04) ◽  
pp. P04034 ◽  
Author(s):  
Shamik Gupta ◽  
Malay Bandyopadhyay
Keyword(s):  
Magnetic Field ◽  
Free Energy ◽  
Heat Bath

WANG–LANDAU SIMULATION ON THERMODYNAMIC AND MAGNETIC PROPERTIES OF HONEYCOMB LATTICE

2011 ◽  
Vol 25 (26) ◽  
pp. 3435-3442
Author(s):  
XIAOYAN YAO
Keyword(s):  
Magnetic Field ◽  
Monte Carlo Simulation ◽  
Magnetic Properties ◽  
Free Energy ◽  
Magnetic Susceptibility ◽  
Magnetic Property ◽  
Ground State ◽  
Antiferromagnetic Order ◽  
Honeycomb Lattice ◽  
Antiferromagnetic Ising Model

Wang–Landau algorithm of Monte Carlo simulation is performed to understand the thermodynamic and magnetic properties of antiferromagnetic Ising model on honeycomb lattice. The internal energy, specific heat, free energy and entropy are calculated to present the thermodynamic behavior. For magnetic property, the magnetization and magnetic susceptibility are discussed at different temperature upon different magnetic field. The antiferromagnetic order is confirmed to be the ground state of the system, and it can be destroyed by a large magnetic field.

Thermodynamics of Bidisperse Ferrofluids in Zero External Magnetic Field: Theory and Simulations

2015 ◽  
Vol 233-234 ◽  
pp. 331-334
Author(s):  
Anna Yu. Solovyova ◽  
Ekaterina A. Elfimova
Keyword(s):  
Magnetic Field ◽  
Field Theory ◽  
Free Energy ◽  
External Magnetic Field ◽  
Volume Concentration ◽  
Helmholtz Free Energy ◽  
Hard Spheres ◽  
Particle Volume ◽  
Simulation Data ◽  
Theoretical Predictions

The thermodynamic properties of a ferrofluid modeled by a bidisperse system of dipolar hard spheres in the absence of external magnetic field are investigated using theory and simulations. The theory is based on the virial expansion of the Helmholtz free energy in terms of particle volume concentration. Comparison between the theoretical predictions and simulation data shows a great agreement of the results.

Formation of non-thermal electron velocity distribution functions in kinetic magnetic reconnection

2021 ◽  
Author(s):  
Xin Yao ◽  
Patricio A. Muñoz ◽  
Jörg Büchner
Keyword(s):  
Magnetic Field ◽  
Free Energy ◽  
Field Strength ◽  
Magnetic Reconnection ◽  
Electron Beams ◽  
Distribution Functions ◽  
Electron Velocity ◽  
Diffusion Region ◽  
Electron Velocity Distribution ◽  
Velocity Distribution Functions

<div> <div>Magnetic reconnection can convert magnetic energy into non-thermal particle energy in the form of electron beams. Those accelerated electrons can, in turn, cause radio emission in environments such as solar flares. The actual properties of those electron velocity distribution functions (EVDFs) generated by reconnection are still not well understood. In particular the properties that are relevant for the micro-instabilities responsible for radio emission. We aim thus at characterizing the electron distributions functions generated by 3D magnetic reconnection by means of fully kinetic particle-in-cell (PIC) code simulations. Our goal is to characterize the possible sources of free energy of the generated EVDFs in dependence on an external (guide) magnetic field strength. We find that: (1) electron beams with positive gradients in their parallel (to the local magnetic field direction) distribution functions are observed in both diffusion region (parallel crescent-shaped EVDFs) and separatrices (bump-on-tail EVDFs). These non-thermal EVDFs cause counterstreaming and bump-on-tail instabilities. These electrons are adiabatic and preferentially accelerated by a parallel electric field in regions where the magnetic moment is conserved. (2) electron beams with positive gradients in their perpendicular distribution functions are observed in regions with weak magnetic field strength near the current sheet midplane. The characteristic crescent-shaped EVDFs (in perpendicular velocity space) are observed in the diffusion region. These non-thermal EVDFs can cause electron cyclotron maser instabilities. These non-thermal electrons in perpendicular velocity space are mainly non-adiabatic. Their EVDFs are attributed to electrons experiencing an E×B drift and meandering motion. (3) As the guide field strength increases, the number of locations in the current sheet with distributions functions featuring a perpendicular source of free energy significantly decreases.</div> </div>

ISING MODEL IN THE MAGNETIC FIELD iπkT/2

1988 ◽  
Vol 02 (03n04) ◽  
pp. 471-481 ◽  
Author(s):  
K. Y. LIN ◽  
F. Y. WU
Keyword(s):  
Magnetic Field ◽  
Free Energy ◽  
Ising Model ◽  
Zero Field ◽  
Two Dimensional ◽  
Anisotropic Interactions ◽  
The Magnetic Field ◽  
Explicit Expressions

It is shown that the free energy and the magnetization of an Ising model in the magnetic field H = iπkT/2 can be obtained directly from corresponding expressions of these quantities in zero field, provided that the latter are known for sufficiently anisotropic interactions. Using this approach we derive explicit expressions of the free energy and the magnetization at H = iπkT/2 for a number of two-dimensional lattices.

scholarly journals Influence of Linear Alkyl Benzene Sulphonate on Corrosion of Iron in Presence of Magnetic Field: Kinetic and Thermodynamic Parameters

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
A. K. Maayta ◽  
Mohammad M. Fares ◽  
Ali F. Al-Shawabkeh
Keyword(s):  
Magnetic Field ◽  
Activation Energy ◽  
Free Energy ◽  
Equilibrium Constant ◽  
Acidic Media ◽  
Alkyl Benzene ◽  
Energy Value ◽  
Linear Alkyl Benzene ◽  
Entropy Increase ◽  
Linear Alkyl Benzene Sulphonate

Implementation of linear alkyl benzene sulphonate, LAS, as corrosion inhibitor on the surface of iron metal in acidic media and in the absence and presence of magnetic field has been investigated. Adsorption of inhibitor molecules on iron surface showed Langmuir adsorption isotherms fit in acidic media. In the absence of magnetic field, apparent activation energy values (Ea) in 2.0 M HCl solutions provide evidence of the inhibitory effect of LAS on iron; similarly, the enthalpy of activation values (ΔH≠) was in accordance with activation energy values. Apparent entropy of activation shows that at larger inhibitor concentration, solvent entropy decrease in 1.0 M HCl and solvent entropy increase in 2.0 M HCl were obtained. Furthermore, spontaneity, through equilibrium constant (Kads.) values and free energy value (ΔGads.) of the adsorption process, shows a drastic decrease upon temperature increase. In the presence of magnetic field, lower rates of corrosion, larger activation energies, solvent entropy increase, larger equilibrium constant (Kads.) value, and lower free energy value (ΔGads.) have been investigated.

scholarly journals Effective electromagnetic lagrangian at finite temperature and density in the electroweak model

Open Physics ◽  
2011 ◽  
Vol 9 (4) ◽  
Author(s):  
Andrea Erdas
Keyword(s):  
Magnetic Field ◽  
Free Energy ◽  
Partition Function ◽  
Field Strength ◽  
Constant Magnetic Field ◽  
Finite Temperature ◽  
Weak Coupling ◽  
Weak Coupling Limit ◽  
Effective Coupling ◽  
Electroweak Model

AbstractUsing the exact propagators in a constant magnetic field, the effective electromagnetic lagrangian at finite temperature and density is calculated to all orders in the field strength B within the framework of the complete electroweak model, in the weak coupling limit. The partition function and free energy are obtained explicitly and the finite temperature effective coupling is derived in closed form. Some implications of this result, potentially interesting to astrophysics and cosmology, are discussed.

THERMODYNAMIC CRITICAL FIELD OF La2-xSrxCuO4

2001 ◽  
Vol 15 (24n25) ◽  
pp. 3156-3163
Author(s):  
YUNG M. HUH ◽  
D. K. FINNEMORE
Keyword(s):  
Magnetic Field ◽  
Free Energy ◽  
Transition Temperature ◽  
Critical Field ◽  
Field Data ◽  
Theoretical Models ◽  
Critical Fields ◽  
Thermodynamic Critical Field ◽  
The Cross

Thermodynamic critical fields, Hc, have been measured for the La2-xSrxCuO4 family of superconductors in order to determine the changes in free energy of the system as the number of carriers is reduced. Magnetization vs. magnetic field curves are thermodynamically reversible over large portions of the H-T plane, so the free energy is well defined in these regions. Magnetization vs. field data are then fit to theoretical models to determine the thermodynamic critical fields. As the Sr concentration is changed from x=0.10 to 0.23, the values of Hc(T=0) goes through a maximum at optimum doping in a manner similar to the Tc vs x curve. The ratio of Hc(T = 0)/Tc also peaks in the region of x somewhat larger than optimum doping. As the value of x increases from underdoped to optimum doping, the cross-over temperature in the Msc vs. T curve, T*, approaches the transition temperature. In the overdoped regime there is no crossing in these Msc vs. T curves.

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