Atomistic modeling of Ru nanocluster formation on graphene/Ru(0001): Thermodynamically versus kinetically directed-assembly

2013 ◽  
Vol 1498 ◽  
pp. 249-254 ◽  
Author(s):  
Y. Han ◽  
A. K. Engstfeld ◽  
C.-Z. Wang ◽  
L. D. Roelofs ◽  
R. J. Behm ◽  
...  
Keyword(s):  
Density Functional ◽  
Lattice Gas ◽  
Kinetic Monte Carlo ◽  
Directed Assembly ◽  
Height Distribution ◽  
Functional Theory ◽  
Atomistic Lattice ◽  
Lattice Gas Models ◽  
Mean Size ◽  
Kinetic Monte Carlo Simulations

ABSTRACTAtomistic lattice-gas models for thermodynamically and kinetically directed assembly are applied to Ru nanocluster formation on a monolayer of graphene supported on Ru(0001) at 309 K. Nanocluster density, mean size, height distribution, and spatial ordering are analyzed by kinetic Monte Carlo simulations. Both models can reproduce the experimental data, but additional density functional theory analysis favors the former.

scholarly journals Migration of Zeolite-Encapsulated Pt and Au Under Reducing Atmospheres

2021 ◽  
Author(s):  
Dianwei Hou ◽  
Christopher Heard
Keyword(s):  
Monte Carlo ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Noble Metals ◽  
Kinetic Monte Carlo ◽  
Pore System ◽  
Kinetic Monte Carlo Simulations ◽  
Zeolite Lta ◽  
Metal Migration ◽  
Energy Surfaces

Unbiased density functional global optimisation calculations, followed by kinetic Monte Carlo simulations are used to enumerate the potential energy surfaces for migration of noble metals Pt and Au inside the pore system of siliceous zeolite LTA. The effects of reducing adsorbates CO and H2 are determined. It is found that the two metals differ significantly in the strength and type of interaction with the framework, with strong, framework breaking interactions between Pt and and the zeolite, but only weak dispersive interactions between Au and the zeolite. Adsorbates are found to dramatically interfere with Pt-framework binding, leading to poorer atom-trapping, enhanced metal migration and faster equilibration.

Carbon Effect on Thermal Ageing Simulations in Ferrite Steels

2012 ◽  
Vol 1444 ◽  
Author(s):  
Fabio Nouchy ◽  
Antoine Claisse ◽  
Pär Olsson
Keyword(s):  
Density Functional ◽  
Interatomic Potential ◽  
Kinetic Monte Carlo ◽  
Time Frame ◽  
Thermal Ageing ◽  
Computational Time ◽  
Carbide Formation ◽  
Monte Carlo Code ◽  
Functional Theory ◽  
Exponential Trend

ABSTRACTTwo major causes of hardening and subsequent embrittlement in ferrite steels are the spinodal decomposition of the binary Fe-Cr solid solution and the carbide formation due to the presence of carbon as foreign interstitial atoms. In the present work, simulations of the microstructure evolution due to thermal ageing are performed by means of a kinetic Monte Carlo code and using a state-of-the-art interatomic potential based on density functional theory (DFT) predictions and experimental data. The main issues concern the possibility to perform thermal ageing simulations in an acceptable computational time frame and to reproduce a realistic behavior of carbon kinetics and carbide formation. The simulations on the binary system show the microstructural evolution during thermal ageing and allowed to find an exponential trend related to the acceleration as a function of temperature. With the insertion of carbon in the model, the chromium precipitation tends to accelerate. The carbon clustering, analyzed separately, is faster with higher C concentrations and in lattices with segregated chromium.

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