Kinetic Analysis on Nanoparticle Condensation by Molecular Dynamics

2013 ◽  
Vol 135 (10) ◽  
Author(s):  
Donguk Suh ◽  
Kenji Yasuoka
Keyword(s):  
Molecular Dynamics ◽  
Growth Rate ◽  
Free Energy ◽  
Kinetic Analysis ◽  
Seed Size ◽  
Homogeneous Nucleation ◽  
Cluster Formation ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Seed Particle

Condensation on a cubic seed particle was simulated by classical molecular dynamics (MD). Seed size and supersaturation ratio of the system were the factors that were examined in order to observe the effects of the dimension of seeds and thermodynamic conditions. Two stages of nucleation were observed in the phenomenon, where the first stage is from the seed growth and the second from homogeneous nucleation. Therefore, the nucleation rate and growth rate were each calculated by the Yasuoka–Matsumoto (YM) method. As the seed size increased, the growth rate decreased, but there was no clear seed influence on the homogeneous nucleation characteristics. Besides, the classical nucleation theory (CNT), cluster formation free energy and kinetic analysis were conducted. The free energy in the exponential term of the classical nucleation theory and that obtained from the cluster formation free energy showed different characteristics.

Kinetic Analysis on Nanoparticle Condensation by Molecular Dynamics

2012 ◽  
Author(s):  
Donguk Suh ◽  
Kenji Yasuoka
Keyword(s):  
Molecular Dynamics ◽  
Growth Rate ◽  
Free Energy ◽  
Kinetic Analysis ◽  
Seed Size ◽  
Homogeneous Nucleation ◽  
Cluster Formation ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Seed Particle

Condensation on a cubic seed particle was simulated by classical molecular dynamics. Seed size and supersaturation ratio of the system were the factors that were examined in order to observe the effects of the dimension of seeds and thermodynamic conditions. Two stages of nucleation were observed in the phenomenon, where the first stage is from the seed growth and the second from homogeneous nucleation. Therefore, the nucleation rate and growth rate were each calculated by the Yasuoka-Matsumoto method. As seed size increased the growth rate decreased, but there was no clear seed influence on the homogeneous nucleation characteristics. Besides the classical nucleation theory, cluster formation free energy and kinetic analysis were conducted. The free energy in the exponential term of the classical nucleation theory and that obtained from the cluster formation free energy showed different characteristics.

Molecular Dynamics Based Analysis of Nucleation and Surface Energy of Droplets in Supersaturated Vapors of Methane and Ethane

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Jadran Vrabec ◽  
Martin Horsch ◽  
Hans Hasse
Keyword(s):  
Molecular Dynamics ◽  
Surface Energy ◽  
Droplet Size ◽  
Nucleation Rate ◽  
Homogeneous Nucleation ◽  
First Passage Time ◽  
Nucleation Theory ◽  
Dynamics Simulation ◽  
Classical Nucleation Theory ◽  
Critical Droplet

Homogeneous nucleation processes are characterized by the nucleation rate and the critical droplet size. Molecular dynamics simulation is applied for studying homogeneous nucleation during condensation of supersaturated vapors of methane and ethane. The results are compared with the classical nucleation theory (CNT) and the Laaksonen–Ford–Kulmala (LFK) model that introduces the size dependence of the specific surface energy. It is shown for the nucleation rate that the Yasuoka–Matsumoto method and the mean first passage time method lead to considerably differing results. Even more significant deviations are found between two other approaches to the critical droplet size, based on the maximum of the Gibbs free energy of droplet formation (Yasuoka–Matsumoto) and the supersaturation dependence of the nucleation rate (nucleation theorem). CNT is found to agree reasonably well with the simulation results, whereas LFK leads to large deviations at high temperatures.

Homogeneous nucleation of NaCl in supersaturated solutions

2021 ◽  
Author(s):  
Cintia Pulido Lamas ◽  
Jorge R. Espinosa ◽  
María Martín Conde ◽  
Jorge Ramirez ◽  
Pablo Montero de Hijes ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Homogeneous Nucleation ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Approximate Approach ◽  
Seeding Method ◽  
Dynamics Simulations ◽  
Supersaturated Solutions

The Seeding method is an approximate approach to investigate nucleation that combines molecular dynamics simulations with classical nucleation theory. This technique has been successfully implemented in a broad range of...

Molecular Dynamics Based Analysis of Nucleation and Surface Energy of Droplets in Supersaturated Vapors of Methane and Ethane

2008 ◽  
Author(s):  
Jadran Vrabec ◽  
Martin Horsch ◽  
Hans Hasse
Keyword(s):  
Molecular Dynamics ◽  
Surface Energy ◽  
Nucleation Rate ◽  
Homogeneous Nucleation ◽  
Size Dependence ◽  
Md Simulations ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Specific Surface Energy ◽  
Simulation Results

Molecular dynamics (MD) simulations are applied for studying homogeneous nucleation during condensation of supersaturated vapors of methane and ethane. Nucleation processes are characterized by the nucleation rate, i.e. the number of stable droplets produced per volume and time. Nucleation rates from simulations are compared to the classical nucleation theory (CNT) and a model that introduces a size dependence of the specific surface energy. CNT is found to agree well with the simulation results, deviations are throughout lower than three orders of magnitude.

Molecular Dynamics Simulation of Three-Dimensional Heterogeneous Nucleation

2011 ◽  
Author(s):  
Donguk Suh ◽  
Kenji Yasuoka
Keyword(s):  
Molecular Dynamics ◽  
Heterogeneous Nucleation ◽  
Homogeneous Nucleation ◽  
Three Dimensional ◽  
Nucleation Theory ◽  
Dynamics Simulation ◽  
Classical Nucleation Theory ◽  
Supersaturation Ratio ◽  
Seed Growth ◽  
Thermodynamic Conditions

Nanoparticle growth based on three-dimensional heterogeneous nucleation was simulated by classical molecular dynamics. To collectively observe the effects of the dimension of seeds and thermodynamic conditions, seed size and system supersaturation ratio were the factors that were examined to see if they influenced the nucleation rates. Two stages were found to exist within the system, where the first stage is from the seed growth and the second from homogeneous nucleation. The Yasuoka-Matsumoto method was used to calculate the rates. The homogeneous nucleation characteristics coincided with the classical nucleation theory, but heterogeneous nucleation showed an irregular form, which at the current state cannot not be fully understood. Kinetic analysis was also performed to calculate the critical nucleus size and better understand the seed growth characteristics. All in all, the seed effects were insignificant to the overall nucleation characteristics for this system.

scholarly journals Low-temperature nucleation anomaly in silicate glasses shown to be artifact in a 5BaO·8SiO2 glass

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xinsheng Xia ◽  
D. C. Van Hoesen ◽  
Matthew E. McKenzie ◽  
Randall E. Youngman ◽  
K. F. Kelton
Keyword(s):  
Nucleation Rate ◽  
Experimental Approach ◽  
Cluster Formation ◽  
Heating Time ◽  
Silicate Glasses ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Real Phenomenon ◽  
Satisfactory Answer ◽  
Over 40 Years

AbstractFor over 40 years, measurements of the nucleation rates in a large number of silicate glasses have indicated a breakdown in the Classical Nucleation Theory at temperatures below that of the peak nucleation rate. The data show that instead of steadily decreasing with decreasing temperature, the work of critical cluster formation enters a plateau and even starts to increase. Many explanations have been offered to explain this anomaly, but none have provided a satisfactory answer. We present an experimental approach to demonstrate explicitly for the example of a 5BaO ∙ 8SiO2 glass that the anomaly is not a real phenomenon, but instead an artifact arising from an insufficient heating time at low temperatures. Heating times much longer than previously used at a temperature 50 K below the peak nucleation rate temperature give results that are consistent with the predictions of the Classical Nucleation Theory. These results raise the question of whether the claimed anomaly is also an artifact in other glasses.

The Effects of Si on the Nucleation Kinetics of Ferrite in Dual Phase Steels

2007 ◽  
Vol 26-28 ◽  
pp. 1307-1310 ◽  
Author(s):  
Sang Hwan Lee ◽  
Kyung Jong Lee
Keyword(s):  
Free Energy ◽  
Interfacial Energy ◽  
Free Energy Change ◽  
Nucleation Theory ◽  
Energy Change ◽  
Classical Nucleation Theory ◽  
Nucleation Kinetics ◽  
Kinetics Of ◽  
Volume Free Energy Change ◽  
Thermodynamic Factors

It is generally accepted that Si promotes kinetics of polygonal ferrite due to thermodynamic factors such as Ae3 and maximum amount of ferrite formed. However, in this study, it was found that the difference between the measured rates of ferrite formation in C-Mn steel and Si added steel was much larger than that expected considering only thermodynamic factors. The classical nucleation theory with pillbox model was adopted to figure out what is the most controlling factor in formation of ferrite. The volume free energy change was calculated by use of the dilute solution model. The diffusivity of carbon (DC) was formulated as functions of C, Mn and Si by using experimental data. It was found that the volume free energy change was still predominant but the kinetic factors such as interfacial energy and the diffusivity of carbon by addition of Si were not negligible at lower undercooling. However, with increasing undercooling, the diffusivity of C was the most effective on the ferrite kinetics, though the ambiguity of treating interfacial energy was not yet clear.

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