scholarly journals A computational study of the interaction of organic surfactants with goethite α-FeO(OH) surfaces

RSC Advances ◽  
2016 ◽  
Vol 6 (94) ◽  
pp. 91893-91903 ◽  
Author(s):  
David Santos-Carballal ◽  
Zhimei Du ◽  
Helen E. King ◽  
Nora H. de Leeuw
Keyword(s):  
Carboxylic Acids ◽  
Computational Study ◽  
Atomistic Simulations ◽  
Interatomic Potentials

Atomistic simulations based on interatomic potentials show that a range of carboxylic acids adsorb to goethite surfaces.

A computational study on the mechanism of ynamide-mediated amide bond formation from carboxylic acids and amines

2017 ◽  
Vol 15 (30) ◽  
pp. 6367-6374 ◽  
Author(s):  
Song-Lin Zhang ◽  
Hai-Xing Wan ◽  
Zhu-Qin Deng
Keyword(s):  
Reaction Mechanism ◽  
Carboxylic Acids ◽  
Computational Study ◽  
Bond Formation ◽  
Amide Bond ◽  
Reactivity Pattern ◽  
Amide Bond Formation ◽  
Coupling Reagent ◽  
Catalytic Effects ◽  
Acid Substrate

A detailed computational study is presented on the reaction mechanism of ynamide-mediated condensation of carboxylic acids with amines to produce amides, which elucidates the reactivity pattern of the coupling reagent ynamide and discloses crucial bifunctional catalytic effects of the carboxylic acid substrate during aminolysis.

scholarly journals Growth modification of seeded calcite using carboxylic acids: Atomistic simulations

2010 ◽  
Vol 346 (1) ◽  
pp. 226-231 ◽  
Author(s):  
Ulrich Aschauer ◽  
Dino Spagnoli ◽  
Paul Bowen ◽  
Stephen C. Parker
Keyword(s):  
Carboxylic Acids ◽  
Atomistic Simulations ◽  
Growth Modification

On the impact of lattice parameter accuracy of atomistic simulations on the microstructure of Ni-Ti shape memory alloys

2021 ◽  
Author(s):  
Lorenzo La Rosa ◽  
Francesco Maresca
Keyword(s):  
Molecular Dynamics ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Lattice Parameter ◽  
Lattice Parameters ◽  
Atomistic Simulations ◽  
Interatomic Potentials ◽  
The Impact

Abstract Ni-Ti is a key shape memory alloy (SMA) system for applications, being cheap and having good mechanical properties. Recently, atomistic simulations of Ni-Ti SMAs have been used with the purpose of revealing the nano-scale mechanisms that control superelasticity and the shape memory effect, which is crucial to guide alloying or processing strategies to improve materials performance. These atomistic simulations are based on molecular dynamics modelling that relies on (empirical) interatomic potentials. These simulations must reproduce accurately the mechanism of martensitic transformation and the microstructure that it originates, since this controls both superelasticity and the shape memory effect. As demonstrated by the energy minimization theory of martensitic transformations [Ball, James (1987) Archive for Rational Mechanics and Analysis, 100:13], the microstructure of martensite depends on the lattice parameters of the austenite and the martensite phases. Here, we compute the bounds of possible microstructural variations based on the experimental variations/uncertainties in the lattice parameter measurements. We show that both density functional theory and molecular dynamics lattice parameters are typically outside the experimental range, and that seemingly small deviations from this range induce large deviations from the experimental bounds of the microstructural predictions, with notable cases where unphysical microstructures are predicted to form. Therefore, our work points to a strategy for benchmarking and selecting interatomic potentials for atomistic modelling of shape memory alloys, which is crucial to modelling the development of martensitic microstructures and their impact on the shape memory effect.

Redshift or Adduct Stabilization—A Computational Study of Hydrogen Bonding in Adducts of Protonated Carboxylic Acids

2009 ◽  
Vol 15 (2) ◽  
pp. 239-248 ◽  
Author(s):  
Solveig Gaarn Olesen ◽  
Steen Hammerum
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Bond Strength ◽  
Bond Length ◽  
Carboxylic Acids ◽  
Computational Study ◽  
Proton Affinities ◽  
Oh Groups ◽  
Hydrogen Bond Strength ◽  
Length Changes

It is generally expected that the hydrogen bond strength in a D–H•••A adduct is predicted by the difference between the proton affinities (Δ PA) of D and A, measured by the adduct stabilization, and demonstrated by the infrared (IR) redshift of the D–H bond stretching vibrational frequency. These criteria do not always yield consistent predictions, as illustrated by the hydrogen bonds formed by the E and Z OH groups of protonated carboxylic acids. The Δ PA and the stabilization of a series of hydrogen bonded adducts indicate that the E OH group forms the stronger hydrogen bonds, whereas the bond length changes and the redshift favor the Z OH group, matching the results of NBO and AIM calculations. This reflects that the thermochemistry of adduct formation is not a good measure of the hydrogen bond strength in charged adducts, and that the ionic interactions in the E and Z adducts of protonated carboxylic acids are different. The OH bond length and IR redshift afford the better measure of hydrogen bond strength.

scholarly journals Thermodynamics of the Atomic Distribution in Pt3Pd2, Pt2Pd3 and their Corresponding (111) Surfaces

2021 ◽  
Vol 74 ◽  
Author(s):  
Kyle Meerholz ◽  
David Santos-Carballal ◽  
Umberto Terranova ◽  
Anzel Falch ◽  
Cornelia G.C.E. van Sittert ◽  
...  
Keyword(s):  
Solid State ◽  
Bimetallic Catalysts ◽  
Computational Study ◽  
Interatomic Potentials ◽  
Site Occupation ◽  
Surface Energies ◽  
General Utility ◽  
Production Of Hydrogen ◽  
Surface Models ◽  
State Models

ABSTRACT In this study, we have developed solid-state models of platinum and palladium bimetallic catalysts, Pt3Pd2 and Pt2Pd3, which are rapidly thermally annealed at 800 °C. These models were constructed by determining all the unique atomic configurations in a 2x2x1 supercell, using the program Site-Occupation Disorder (SOD), and optimized with the General Utility Lattice Program (GULP) using Sutton-Chen interatomic potentials. Each catalyst had 101 unique bulk models that were developed into surface models, which were constructed using the two-region surface technique before the surface energies were determined. The planes and compositions with lowest surface energies were chosen as the representative models for the surface structure of the bimetallic catalysts. These representative models will now be used in a computational study of the HyS process for the production of hydrogen. Keywords: HyS process, platinum, palladium, solid-state, catalyst, Site-Occupation Disorder.

Atomistic Simulations for Multiscale Modeling in bcc Metals

1999 ◽  
Vol 121 (2) ◽  
pp. 120-125 ◽  
Author(s):  
John A. Moriarty ◽  
Wei Xu ◽  
Per So¨derlind ◽  
James Belak ◽  
Lin H. Yang ◽  
...  
Keyword(s):  
Multiscale Modeling ◽  
Strength Properties ◽  
Peierls Stress ◽  
Boundary Structure ◽  
Atomistic Simulations ◽  
Interatomic Potentials ◽  
Ideal Strength ◽  
Bcc Metals ◽  
Kink Pair ◽  
Grain Boundary Structure

Quantum-based atomistic simulations are being used to study fundamental deformation and defect properties relevant to the multiscale modeling of plasticity in bcc metals at both ambient and extreme conditions. Ab initio electronic-structure calculations on the elastic and ideal-strength properties of Ta and Mo help constrain and validate many-body interatomic potentials used to study grain boundaries and dislocations. The predicted Σ5 (310) [100] grain boundary structure for Mo has recently been confirmed in HREM measurements. The core structure, γ surfaces, Peierls stress, and kink-pair formation energies associated with the motion of a/2〈111〉 screw dislocations in Ta and Mo have also been calculated. Dislocation mobility and dislocation junction formation and breaking are currently under investigation.

Atomistic simulations of TeO2-based glasses: interatomic potentials and molecular dynamics

2014 ◽  
Vol 16 (27) ◽  
pp. 14150-14160 ◽  
Author(s):  
Anastasia Gulenko ◽  
Olivier Masson ◽  
Abid Berghout ◽  
David Hamani ◽  
Philippe Thomas
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Interatomic Potential ◽  
Atomistic Simulations ◽  
Interatomic Potentials ◽  
First Results ◽  
Dynamics Simulations

This article derives the interatomic potential for the TeO2 system and presents the first results of molecular dynamics simulations of the pure TeO2 structure.

Can Nematic Transitions Be Predicted By Atomistic Simulations? A Computational Study of The Odd–Even Effect

ChemPhysChem ◽  
2004 ◽  
Vol 5 (1) ◽  
pp. 104-111 ◽  
Author(s):  
Roberto Berardi ◽  
Luca Muccioli ◽  
Claudio Zannoni
Keyword(s):  
Computational Study ◽  
Atomistic Simulations
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