Reactive Force Fields: Concepts of ReaxFF

Duin, Adri van

doi:10.1002/9783527625482.ch9

Cited by 15 publications

(11 citation statements)

References 30 publications

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“…A time-step of up to 0.5 fs could be used for simulations at low and normal temperatures, while a smaller time-step is needed for a higher temperature (>1500 K). 992 …”

Section: Classical Modeling Of Metal Ions: the Polarizable Modelmentioning

confidence: 99%

Metal Ion Modeling Using Classical Mechanics

2017

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Metal ions play significant roles in numerous fields including chemistry, geochemistry, biochemistry, and materials science. With computational tools increasingly becoming important in chemical research, methods have emerged to effectively face the challenge of modeling metal ions in the gas, aqueous, and solid phases. Herein, we review both quantum and classical modeling strategies for metal ion-containing systems that have been developed over the past few decades. This Review focuses on classical metal ion modeling based on unpolarized models (including the nonbonded, bonded, cationic dummy atom, and combined models), polarizable models (e.g., the fluctuating charge, Drude oscillator, and the induced dipole models), the angular overlap model, and valence bond-based models. Quantum mechanical studies of metal ion-containing systems at the semiempirical, ab initio, and density functional levels of theory are reviewed as well with a particular focus on how these methods inform classical modeling efforts. Finally, conclusions and future prospects and directions are offered that will further enhance the classical modeling of metal ion-containing systems.

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“…A time-step of up to 0.5 fs could be used for simulations at low and normal temperatures, while a smaller time-step is needed for a higher temperature (>1500 K). 992 …”

Section: Classical Modeling Of Metal Ions: the Polarizable Modelmentioning

confidence: 99%

Metal Ion Modeling Using Classical Mechanics

2017

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“…MD simulations were performed using the reactive force field (ReaxFF) and Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) . The reverse osmosis system was modeled using Packmol, while the open visualization tool (OVITO) and visual molecular dynamics (VMD) were used for visualization and some analysis.…”

Section: Methodsmentioning

confidence: 99%

Nanoporous MoS₂ Membrane for Water Desalination: A Molecular Dynamics Study

et al. 2021

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Molybdenum disulfide (MoS2), a two-dimensional (2D) material, promises better desalination efficiency, benefiting from the small diffusion length. While the monolayer nanoporous MoS2 membrane has great potential in the reverse osmosis (RO) desalination membrane, multilayer MoS2 membranes are more feasible to synthesize and economical than the monolayer MoS2 membrane. Building on the monolayer MoS2 membrane knowledge, the effects of the multilayer MoS2 membrane in water desalination were explored, and the results showed that increasing the pore size from 3 to 6 Å resulted in higher permeability but with lower salt rejection. The salt rejection increases from 85% in a monolayer MoS2 membrane to about 98% in a trilayer MoS2 membrane. When averaged over all three types of membranes studied, the ions rejection follows the trend of trilayer > bilayer > monolayer. Besides, a narrow layer separation was found to play an important role in the successful rejection of salt ions in bilayer and trilayer membranes. This study aims to provide a collective understanding of this high permiselective MoS2 membrane’s realization for water desalination, and the findings showed that the water permeability of the MoS2 monolayer membrane was in the order of magnitude greater than that of the conventional RO membrane and the nanoporous MoS2 membrane can have an important place in the purification of water.

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“…It appears that ReaxFF with its present formalism seems to be unable to simulate correctly and simultaneously both high and low carbon coordination since there is only one carbon type in ReaxFF to deal with different local chemical environments. Unlike popular nonreactive force fields like AMBER and CHARMM, ReaxFF does not employ atom tagging due to the missing description of particles’ self-interaction …”

Section: Description Of the Models And Simulation Methodologymentioning

confidence: 99%

“…The off-diagonal terms that define both bond order and van der Waals pair interactions have been set to −1.0000. This means that we call ReaxFF to compute these terms using an embedded combination rule between the atomic parameter . When tested, the parameterization described above gives excellent results for handling mixed Fe_S and Fe_B surface and bulk systems (see Figures and S5).…”

Section: Description Of the Models And Simulation Methodologymentioning

confidence: 99%

Capturing the Iron Carburization Mechanisms from the Surface to Bulk

et al. 2020

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Reactive force field molecular dynamics is a powerful tool to simulate large-scale reactive events such as catalytic reactions and metallic corrosion, including the carburization or so-called metal dusting corrosion. Building on a vast set of reactive force field parameters, it aims to reduce the gap between computational and experimental observations. However, the production of different versions of reactive force field parameter sets in the past 2 decades demonstrates the challenges faced by developers when attempting to describe correctly and at the same time a broad range of environments, such as the kinetics of CO adsorption, dissociation, and carbon diffusion in iron systems. This has limited the ability of these force fields to capture the competing phenomena governing complex evolution such as the carburization of iron responsible for metal dusting corrosion. In this work, we demonstrate that it is possible to treat very different environments in an integrated way by expanding the ReaxFF parameter set, creating an environment-specific description. This approach enables us to capture both metallic surface-induced dissociation of carbon-containing gases such as carbon monoxide (CO) and atomic carbon bulk diffusion in iron systems within the same simulation setup so far unreachable with previously available force fields. Employing this extended-ReaxFF to describe a cell containing a gas mixture of carbon monoxide and argon reacting with an Fe(110) surface, we fully capture at the same time competing carburization reaction/diffusion processes on both the surface and the bulk. Analysis of the radial distribution function and charge density maps shows a variety of carbon bonds at different stages/layers, highlighting the diversity of the mechanisms captured while using our extended-ReaxFF. Interestingly, at a CO coverage higher than 0.7 monolayers, the atomic arrangement of the iron atoms is sufficiently altered to cause surface reconstruction leading to a significant increase in carbon diffusion. Moreover, we are able to observe and quantify the diffusion of Fe from the bulk toward the upper coke layer, computationally elucidating the slow but continuous coke formation reported experimentally, opening a wide range of opportunities to model various stages of iron carburization mechanisms.

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Reactive Force Fields: Concepts of ReaxFF

Cited by 15 publications

References 30 publications

Metal Ion Modeling Using Classical Mechanics

Metal Ion Modeling Using Classical Mechanics

Nanoporous MoS₂ Membrane for Water Desalination: A Molecular Dynamics Study

Capturing the Iron Carburization Mechanisms from the Surface to Bulk

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Reactive Force Fields: Concepts of ReaxFF

Cited by 15 publications

References 30 publications

Metal Ion Modeling Using Classical Mechanics

Metal Ion Modeling Using Classical Mechanics

Nanoporous MoS2 Membrane for Water Desalination: A Molecular Dynamics Study

Capturing the Iron Carburization Mechanisms from the Surface to Bulk

Contact Info

Product

Resources

About

Nanoporous MoS₂ Membrane for Water Desalination: A Molecular Dynamics Study