On the determination of the ratios of the propagation rate constants on the basis of the MWD of copolymer chains: A new Monte Carlo algorithm

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Ryszard Szymanski
Keyword(s):  
Monte Carlo ◽  
Rate Constants ◽  
Propagation Rate ◽  
Monte Carlo Algorithm ◽  
Copolymer Chain ◽  
Computation Algorithms ◽  
Chain Lengths

AbstractPossibility of determination of the relations among homo- and crosspropagation rate constants on the basis of analysis of the detailed distribution of copolymer chain lengths is presented. Importance of application of correct computation algorithms in Monte Carlo modelling of copolymerization is indicated. A new algorithm for Monte Carlo modelling of polymerization processes is proposed.

Determination of propagation rate constants using a pulsed laser technique

1989 ◽  
Vol 22 (6) ◽  
pp. 2785-2788 ◽  
Author(s):  
Thomas P. Davis ◽  
Kenneth F. O'Driscoll ◽  
Mark C. Piton ◽  
Mitchell A. Winnik
Keyword(s):  
Rate Constants ◽  
Pulsed Laser ◽  
Propagation Rate ◽  
Laser Technique

Stochastic approximation Monte Carlo algorithm for calculation of diagram of states of a single flexible-semiflexible copolymer chain

2016 ◽  
Vol 58 (6) ◽  
pp. 899-915 ◽  
Author(s):  
Sergey V. Zablotskiy ◽  
Julia A. Martemyanova ◽  
Viktor A. Ivanov ◽  
Wolfgang Paul
Keyword(s):  
Monte Carlo ◽  
Stochastic Approximation ◽  
Monte Carlo Algorithm ◽  
Copolymer Chain

scholarly journals Microscopic Rate Constants of Crystal Growth from Molecular Dynamic Simulations Combined with Metadynamics

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Dániel Kozma ◽  
Gergely Tóth
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Free Energy ◽  
Crystal Growth ◽  
Rate Constants ◽  
Kinetic Monte Carlo ◽  
State Theory ◽  
Free Energy Surface ◽  
Kinetic Monte Carlo Simulation

Atomistic simulation of crystal growth can be decomposed into two steps: the determination of the microscopic rate constants and a mesoscopic kinetic Monte Carlo simulation. We proposed a method to determine kinetic rate constants of crystal growth. We performed classical molecular dynamics on the equilibrium liquid/crystal interface of argon. Metadynamics was used to explore the free energy surface of crystal growth. A crystalline atom was selected at the interface, and it was displaced to the liquid phase by adding repulsive Gaussian potentials. The activation free energy of this process was calculated as the maximal potential energy density of the Gaussian potentials. We calculated the rate constants at different interfacial structures using the transition state theory. In order to mimic real crystallization, we applied a temperature difference in the calculations of the two opposite rate constants, and they were applied in kinetic Monte Carlo simulation. The novelty of our technique is that it can be used for slow crystallization processes, while the simple following of trajectories can be applied only for fast reactions. Our method is a possibility for determination of elementary rate constants of crystal growth that seems to be necessary for the long-time goal of computer-aided crystal design.

scholarly journals A fast, primary-interaction Monte Carlo methodology for determination of total efficiency of cylindrical scintillation gamma-ray detectors

2009 ◽  
Vol 24 (3) ◽  
pp. 195-203 ◽  
Author(s):  
Shakeel Rehman ◽  
Sikander Mirza ◽  
Nasir Mirza
Keyword(s):  
Monte Carlo ◽  
Point Sources ◽  
Monte Carlo Algorithm ◽  
Total Efficiency ◽  
Axial Distance ◽  
Detector Efficiency ◽  
Wide Range ◽  
Energy Dependent ◽  
Primary Interaction

A primary-interaction based Monte Carlo algorithm has been developed for determination of the total efficiency of cylindrical scintillation g-ray detectors. This methodology has been implemented in a Matlab based computer program BPIMC. For point isotropic sources at axial locations with respect to the detector axis, excellent agreement has been found between the predictions of the BPIMC code with the corresponding results obtained by using hybrid Monte Carlo as well as by experimental measurements over a wide range of g-ray energy values. For off-axis located point sources, the comparison of the BPIMC predictions with the corresponding results obtained by direct calculations as well as by conventional Monte Carlo schemes shows good agreement validating the proposed algorithm. Using the BPIMC program, the energy dependent detector efficiency has been found to approach an asymptotic profile by increasing either thickness or diameter of scintillator while keeping the other fixed. The variation of energy dependent total efficiency of a 3'x3' NaI(Tl) scintillator with axial distance has been studied using the BPIMC code. About two orders of magnitude change in detector efficiency has been observed for zero to 50 cm variation in the axial distance. For small values of axial separation, a similar large variation has also been observed in total efficiency for 137Cs as well as for 60Co sources by increasing the axial-offset from zero to 50 cm.

Reverse Monte Carlo Analysis of Powder Patterns

1996 ◽  
Vol 29 (3) ◽  
pp. 285-290 ◽  
Author(s):  
W. Montfrooij ◽  
R. L. McGreevy ◽  
R. Hadfield ◽  
N. H. Andersen
Keyword(s):  
Monte Carlo ◽  
Bragg Peak ◽  
Monte Carlo Analysis ◽  
Monte Carlo Algorithm ◽  
Reverse Monte Carlo ◽  
Peak Intensity ◽  
Thermal Displacements ◽  
Diffraction Patterns ◽  
Best Fit

A Monte Carlo algorithm for the analysis of powder diffraction patterns is presented. One aim of this algorithm, which can be used as a supplement to the regular Rietveld refinement, is to provide a self-consistent determination of the thermal displacements of the atoms. This is achieved by modelling the total scattered intensity, comprising both the Bragg peak intensity and the diffuse contribution to the spectrum from the scattering density of an assembly of atoms. This assembly, which is constructed by the reverse Monte Carlo technique so as to yield a best fit with the data, is then used to calculate the average atomic thermal displacements. This allows for a refinement that, in principle, no longer requires angle-dependent background parameters, and that is well suited for dealing with highly anisotropic Debye–Waller factors and split atomic sites.

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