A new approach to diffusion-limited reaction rate theory

2011 ◽  
Vol 20 (3) ◽  
pp. 260-271 ◽  
Author(s):  
M. S. Veshchunov
Keyword(s):  
Reaction Rate ◽  
Rate Theory ◽  
New Approach ◽  
Diffusion Limited ◽  
Reaction Rate Theory ◽  
Diffusion Limited Reaction

Diffusion-limited reaction rate theory for two-dimensional systems

1983 ◽  
Vol 387 (1792) ◽  
pp. 147-170 ◽  
Keyword(s):  
Reaction Rate ◽  
Rate Function ◽  
Three Dimensions ◽  
Square Lattice ◽  
Rate Theory ◽  
Two Dimensional ◽  
Irreversible Reaction ◽  
Diffusion Limited ◽  
Condensed Phase Reactions ◽  
Diffusion Limited Reaction

The Noyes and Smoluehowski diffusion-limited reaction rate theories are proved to be equivalent on a lattice. The Noyes theory is analysed and used to predict the kinetics of the two-dimensional irreversible reaction A + B → P. Only condensed phase reactions with molecules of A and B undergoing Brownian motion (diffusion) are discussed. For comparison, all calculations are done in both two and three dimensions. The two-dimensional rate function k N ( t ) in the equation d[A]/d t = d[B]/d t = - k N ( t ) [A] [B] asymptotically goes to zero as (In t ) -1 as t increases; the asymptotic expansion of k N ( t ) is derived from the expansion for the first-return probability in a random walk on a square lattice. The theoretical rate function is determined as a function of the probability α of reaction given an encounter. Although k N ( t ) is not significantly different from ‘empirical’ rate functions in a Monte Carlo simulation of a two-dimensional chemical reaction, it does differ from the rate function in a two-dimensional fluorescence quenching experiment.

Thermal Decomposition Kinetics of Glyphosate (GP) and its Metabolite Aminomethylphosphonic Acid (AMPA)

2019 ◽  
Author(s):  
Milad Narimani ◽  
Gabriel da Silva
Keyword(s):  
Thermal Decomposition ◽  
Reaction Rate ◽  
Decomposition Kinetics ◽  
Rate Theory ◽  
Thermal Decomposition Mechanism ◽  
Treatment Processes ◽  
Aminomethylphosphonic Acid ◽  
Reaction Rate Theory ◽  
Decomposition Chemistry ◽  
Kinetics Of

Glyphosate (GP) is a widely used herbicide worldwide, yet accumulation of GP and its main byproduct, aminomethylphosphonic acid (AMPA), in soil and water has raised concerns about its potential effects to human health. Thermal treatment processes are one option for decontaminating material containing GP and AMPA, yet the thermal decomposition chemistry of these compounds remains poorly understood. Here, we have revealed the thermal decomposition mechanism of GP and AMPA by applying computational chemistry and reaction rate theory methods. <br>

Ab Initio Computation of Thermochemistry and Kinetics in the Oxidation of Gas Phase Silicon Species

1992 ◽  
Vol 282 ◽  
Author(s):  
Michael R. Zachariah ◽  
Wing Tsang
Keyword(s):  
Ab Initio ◽  
Gas Phase ◽  
Energy Barrier ◽  
Reaction Rate ◽  
Rate Theory ◽  
Molecular Orbital Calculations ◽  
Activation Energy Barrier ◽  
Ab Initio Computation ◽  
Oxygen Donor ◽  
Reaction Rate Theory

ABSTRACTAb initio molecular orbital calculations coupled to RRKM reaction rate theory have been conducted on some important reactions involved in the oxidation of silane in a high-temperature/high H2O environment. The results indicate thatH2O acts as an oxygen donor to SiH2 to form H3SiOH or SiH2O. Subsequent reactions involve the formation of (HSiOOH, H2Si(OH)2,:Si(OH)2 or SiO). In turn SiO polymerizes into planar rings, without an activation energy barrier. A list of calculated thermochemical data are also presented for a number of equilibrium species.

scholarly journals A Unified Constitutive Model for Creep and Cyclic Viscoplasticity Behavior Simulation of Steels Based on the Absolute Reaction Rate Theory

2017 ◽  
Vol 2017 ◽  
pp. 1-13
Author(s):  
Huayan Chen ◽  
Xiangguo Zeng ◽  
Yang Guo ◽  
Fang Wang
Keyword(s):  
Constitutive Model ◽  
Reaction Rate ◽  
Internal State ◽  
Rate Theory ◽  
State Variables ◽  
Absolute Reaction Rate Theory ◽  
Reaction Rate Theory ◽  
Absolute Reaction Rate ◽  
The Absolute ◽  
Absolute Reaction

In this work, the viscoplasticity and creep behavior for modified 9Cr-1Mo and 316 stainless steels were investigated. Based on the absolute reaction rate theory, a unified constitutive model incorporating internal state variables was proposed to characterize the evolution of the back stress. Also, the model was implemented by the ABAQUS system with the semi-implicit stress integration. Compared to the experimental data, the results demonstrated that the proposed approach could effectively simulate the cyclic softening and hardening behavior for such structural steels.

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