Modeling of Diffusion in Ordered Structures of B2-Type

1998 ◽  
Vol 527 ◽  
Author(s):  
M.G. Ganchenkova ◽  
A.V. Nazarov
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Nearest Neighbor ◽  
Diffusion Mechanism ◽  
Relaxation Technique ◽  
Interatomic Potentials ◽  
Nearest Neighbour ◽  
Ordered Structures ◽  
Activation Barriers ◽  
Static Relaxation

ABSTRACTUsing Monte Carlo simulation, we model the effect of interaction of vacancies on their diffusivities in ordered structures of B2-type. The activation barriers of atom jumps to vacancy are calculated by the static relaxation technique using interatomic potentials for both vacancy exchanges: with nearest-neighbour atoms and next-nearest-neighbour atoms. This is done for all possible positions of the second vacancy. Knowing these barriers it is possible to calculate the jump rates and to model the vacancy migration. The calculations were done for a system with parameters similar to NiAl. The modeling allows to inter the existence of a new diffusion mechanism in ordered structures of B2-type, which could be attributable to dynamic pair of vacancies and vacancy exchanges with next-nearest-neighbor atoms.

MONTE CARLO SIMULATION OF ISING-LIKE IMMUNOLOGICAL SHAPE SPACE

1994 ◽  
Vol 05 (03) ◽  
pp. 513-518 ◽  
Author(s):  
DIETRICH STAUFFER
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Immune System ◽  
Response Curve ◽  
Nearest Neighbor ◽  
Shape Space ◽  
High Dimensional ◽  
Immune Systems ◽  
Probabilistic Generalization ◽  
Dimensional Shape

The high-dimensional shape space for the antibodies of the immune system is simulated with an Ising-like interaction. However, instead of the molecular field being linear in the sum of the neighbor spins, we take it as quadratic and negative. In this way the bell-shaped response curve of biological immune systems is approximated, as a probabilistic generalization of window automata. We find phase transitions only in five and more dimensions, not in two to four, for nearest-neighbor interactions.

Modeling Recrystallization in Aluminum Using Input from Experimental Observations

2007 ◽  
Vol 558-559 ◽  
pp. 1057-1061 ◽  
Author(s):  
Abhijit P. Brahme ◽  
Joseph M. Fridy ◽  
Anthony D. Rollett
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Aluminum Alloys ◽  
Grain Boundary ◽  
Microstructural Evolution ◽  
Nearest Neighbor ◽  
Electron Back Scatter Diffraction ◽  
Effect Of Temperature ◽  
Model Predictions ◽  
Boundary Properties

A model has been constructed for the microstructural evolution that occurs during the annealing of aluminum alloys. Geometric and crystallographic observations from two orthogonal sections through a polycrystal using automated Electron Back-Scatter Diffraction (EBSD) were used as an input to the computer simulations to create a statistically representative threedimensional model. The microstructure is generated using a voxel-based tessellation technique. Assignment of orientations to the grains is controlled to ensure that both texture and nearest neighbor relationships match the observed distributions. The microstructures thus obtained are allowed to evolve using a Monte-Carlo simulation. Anisotropic grain boundary properties are used in the simulations. Nucleation is done in accordance with experimental observations on the likelihood of occurrences in particular neighborhoods. We will present the effect of temperature on the model predictions.

An AB Initio Calculation of the Pd-V FCC Superstructure Phase Diagram with Fourth Nearest Neighbor Cluster Interactions

1992 ◽  
Vol 291 ◽  
Author(s):  
Patrick D. Tepesch ◽  
G. Ceder ◽  
C. Wolverton ◽  
D. De Fontaine
Keyword(s):  
Phase Diagram ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Ab Initio Calculation ◽  
Nearest Neighbor ◽  
Tight Binding ◽  
Monte Carlo Simulation Technique ◽  
Experimental Diagram ◽  
Neighbor Cluster ◽  
Independent Pair

ABSTRACTThe Monte Carlo technique was used to calculate the phase diagram of the fee superstructures in the Pd-V system using up to fourth nearest neighbor, concentration independent, pair and multiplet interactions. The interactions were computed by the method of Direct Configurational Averaging using a Linearized Muffin-Tin Orbital Hamiltonian cast into the tight binding form. The phase diagram was computed with a fast Monte Carlo simulation technique using environment sampling. The two fee ground states in experimental diagram are predicted to be stable. The computed transition temperatures are higher than those found experimentally.

scholarly journals Distribution of defects in lipid membranes. Computer simulation

2014 ◽  
Vol 65 (3-4) ◽  
pp. 257-260 ◽  
Author(s):  
Witold Okulski
Keyword(s):  
Computer Simulation ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Lipid Membranes ◽  
Lipid Membrane ◽  
Ion Transfer ◽  
Nearest Neighbour ◽  
The Monte Carlo Method ◽  
Temperature Dependences ◽  
Lipid Chain

Based on the Monte-Carlo method, the ten-state Pink model of lipid membrane was completed by the dynamic Kawasaki-type processes of nearest neighbour exchanges of lipid molecules and vacancies in lipid chain lattice. The influence of the number and distribution of vacancies in membrane on its permeability was studied. The snapshots of microconfigurations of the dipalmitoylphosphatidylcholine (DPPC) membrane model obtained from Monte-Carlo simulation were analyzed. Temperature dependences of the area of vacancies in the membrane and regional probability of an ion transfer through interface region were determined.

Critical behavior of Pr0.65Sr0.35MnO3 compound investigated by a Monte Carlo simulation

2020 ◽  
Author(s):  
Lhaj el Hachemi Omari ◽  
Abdelmajid Lekdadri ◽  
Rachid Chami ◽  
El Kibir Hlil
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Ising Model ◽  
Curie Temperature ◽  
Critical Behavior ◽  
Nearest Neighbor ◽  
Magnetic Behavior ◽  
Cooling Power ◽  
Thermal Bath ◽  
Magnetic Entropy

The critical behavior and magnetic properties of Pr0.65Sr0.35MnO3 (symbolized by PSMO) were studied using Monte Carlo simulation (MCS). The thermal bath algorithm and the Ising model in which exchange interactions via the third nearest neighbor were used to calculate the magnetic and magneto-caloric properties. The effects of temperature (T) and external magnetic field (h) on the magnetic behavior of PSMO were examined. The results show that the Curie temperature (TC) is close to the experimental value. The magnetic entropy shows a maximum value around the TC which increases linearly with the increase of the external field. The expected critical behavior of the PSMO nanoparticles was studied through the isothermal magnetization and from the Arrott plots. The obtained values are β = 0.356, γ = 1.121, and δ = 3.95. These values not so far from those reported for the 3D-Ising model. The variation of maximum magnetic entropy (∆S_m^max) and relative cooling power (RCP) around the Curie temperature were calculated; the resulting values of ∆S_m^max and those of RCP range from 3.612 and 92.7 for 1T to 6.191 and 209.9 for 5T, respectively. These results are sufficiently interesting to consider the PSMO compound as a promising candidate for magnetic refrigeration.

scholarly journals Power Laws in Adsorption and the Characterization of Heterogeneous Substrates

2001 ◽  
Vol 19 (3) ◽  
pp. 229-236 ◽  
Author(s):  
F. Bulnes ◽  
A.J. Ramirez-Pastor ◽  
G. Zgrablich
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Power Laws ◽  
Nearest Neighbour ◽  
Scale Length

The adsorption of particles with repulsive nearest-neighbour interactions was studied through Monte Carlo simulation on bivariate surfaces characterized by patches of weak and strong adsorbing sites of size l. Patches were either arranged in a deterministic chessboard structure or in a random way. Quantities were identified which scale obeying power laws as a function of the scale length l. The consequences of these findings were discussed for the determination of the energetic topography of the surface from adsorption measurements.

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