1,721,173 research outputs found
Data associated to the manuscript "Co-Ion Desorption as the Main Charging Mechanism in Metallic 1T-MoS2 Supercapacitors"
No full textSupporting data for the article:
Co-Ion Desorption as the Main Charging Mechanism in Metallic 1T-MoS2 Supercapacitors
Sheng Bi, Salanne Mathieu, ACS Nano, 2022
https://pubs.acs.org/doi/10.1021/acsnano.2c07272
The folders slab and slit contain typical MetalWalls input files used to perform the simulations for two electrode geometries
Computational Dataset for "Reversible Magnesium and Aluminium-ions Insertion in Cation-Deficient Anatase TiO2"
No full textThis dataset contains the computational data and analysis for the paper "Reversible Magnesium and Aluminium-Ions Insertion in Cation-Deficient Anatase TiO2" (https://doi.org/10.1038/nmat4976).
The repository contains:
1. Input and output files for the DFT calculations, performed using VASP. This is detailed below in the Data section.
2. A `vasp_summary` script, that collects the relevant VASP data into a file `F-TiO2_intercalation_data.yaml`.
3. A Jupyter notebook, `F-TiO2 intercalation energies.ipynb`, containing the data analysis, and code for plotting intercalation energies.
2 and 3 both depend on the vasppy Python module (https://github.com/bjmorgan/vasppy, https://doi.org/10.5281/zenodo.801663), available under the MIT licence.All calculations were performed using VASP 5.3.5. Input files for each calculation are contained within the dataset.
For further details, please see the associated paper, available at
http://opus.bath.ac.uk/57334/.Relevant data (energies of optimised structures) were extracted using the included `vasp_summary`. Intercalation energies and voltages were calculated with the included Jupyter notebook. Both steps use the `vasppy` Python module, available at https://github.com/bjmorgan/vasppy
Modelling and evaluating the consequences of the presence of O2− in NaF–ZrF4 molten fluoride salt
Full text linkThe framework of this study is the potential use of molten salts in the nuclear industry
of the future. Those systems properties have been determined from finite temperature molecular
dynamics simulations with a realistic representation of the interatomic interactions
(the dipole-polarizable ion model, DIPPIM).
Among the quantities that can be obtained from molecular dynamics simulations,
structural and dynamic properties hold particular interest for this work : those are mandatory
to determine the various molten salts capabilities for being used as coolants in
nuclear reactors, or the speciation of fission products in silicate glasses. This work has
been particularly focused on the effect of adding small amounts of oxides in a fluorozirconate
based molten salt. The formation of molecular ions based on strong Zr–O–Zr bonds
results in an important medium-range ordering of the system and in a noticeable slowing
of the dynamics of the ions, accompanied by an increase of the viscosity.
Keywords
Fluoride ionic molten salts, fourth generation nuclear reactor, concentration of oxide,
molecular dynamics, computer simulations, structural study, dynamical analysis, viscosity,
diffusion, NaF–ZrF4.Outgoin
Modelling and evaluating the consequences of the presence of O2− in NaF–ZrF4 molten fluoride salt
No full textThe framework of this study is the potential use of molten salts in the nuclear industry
of the future. Those systems properties have been determined from finite temperature molecular
dynamics simulations with a realistic representation of the interatomic interactions
(the dipole-polarizable ion model, DIPPIM).
Among the quantities that can be obtained from molecular dynamics simulations,
structural and dynamic properties hold particular interest for this work : those are mandatory
to determine the various molten salts capabilities for being used as coolants in
nuclear reactors, or the speciation of fission products in silicate glasses. This work has
been particularly focused on the effect of adding small amounts of oxides in a fluorozirconate
based molten salt. The formation of molecular ions based on strong Zr–O–Zr bonds
results in an important medium-range ordering of the system and in a noticeable slowing
of the dynamics of the ions, accompanied by an increase of the viscosity.
Keywords
Fluoride ionic molten salts, fourth generation nuclear reactor, concentration of oxide,
molecular dynamics, computer simulations, structural study, dynamical analysis, viscosity,
diffusion, NaF–ZrF4.Outgoin
Modelling and evaluating the consequences of the presence of O2− in NaF–ZrF4 molten fluoride salt
No full textThe framework of this study is the potential use of molten salts in the nuclear industry
of the future. Those systems properties have been determined from finite temperature molecular
dynamics simulations with a realistic representation of the interatomic interactions
(the dipole-polarizable ion model, DIPPIM).
Among the quantities that can be obtained from molecular dynamics simulations,
structural and dynamic properties hold particular interest for this work : those are mandatory
to determine the various molten salts capabilities for being used as coolants in
nuclear reactors, or the speciation of fission products in silicate glasses. This work has
been particularly focused on the effect of adding small amounts of oxides in a fluorozirconate
based molten salt. The formation of molecular ions based on strong Zr–O–Zr bonds
results in an important medium-range ordering of the system and in a noticeable slowing
of the dynamics of the ions, accompanied by an increase of the viscosity.
Keywords
Fluoride ionic molten salts, fourth generation nuclear reactor, concentration of oxide,
molecular dynamics, computer simulations, structural study, dynamical analysis, viscosity,
diffusion, NaF–ZrF4.Outgoin
Data sets for "Structure and dynamics of aqueous NaCl solutions at high temperatures and pressures"
No full textData sets used to prepare Figures 1-11, 13-16, 18-19, 21-23, 25-26, 28, 30-31, S1-S9 and S12 in the Journal of Chemical Physics article entitled "Structure and dynamics of aqueous NaCl solutions at high temperatures and pressures." The data sets refer to the structure and dynamics of a solution of 5 molal NaCl in heavy water (D2O).The data sets were collected using the methods described in the published paper.The data sets were analysed using the methods described in the published paper.The figures were prepared using QtGrace (https://sourceforge.net/projects/qtgrace/). The data set corresponding to a plotted curve within an QtGrace file can be identified by clicking on that curve.The files are labelled according to the corresponding figure numbers. The units for each axis are identified on the plots
A molecular density functional theory for the study of electron transfer reactions in realistic systems
No full textLe développement et la vérification de la théorie fonctionnelle de la densité moléculaire (MDFT) est effectuée dans cette thèse dans le but d'étudier des réactions électrochimiques réalistes de transfert d'électrons électrochimiques réalistes. Des prédictions précises des propriétés de transfert d'électrons aux interfaces électrochimiques en utilisant la MDFT nécessitent l'application des méthodes de correction de pression. L'exactitude des deux stratégies de correction de pression à la MDFT proposées dans la littérature a été examinée dans le contexte du transfert d'électrons. Il a été montré que seules les méthodes de correction qui respectent le principe variationnel peuvent être utilisées pour étudier le transfert d'électrons. D'autre part, nous avons montré que la MDFT reproduit très bien les résultats de la structure de solvatation et des propriétés de transfert d'électrons de quinones solvatées dans l'acétonitrile (MeCN) qui sont calculés avec des simulations de dynamique moléculaire (MD) utilisant des champs de force beaucoup plus sophistiqués. Nous profitons ensuite de l'efficacité numérique de la MDFT pour calculer les énergies libres de réorganisation de nombreux dérivés de la 1,4-benzoquinone (BQ). Nous avons trouvé que le transfert d'électrons de tous les dérivés de BQ solvatés dans MeCN peut être bien décrit par la théorie de Marcus. Enfin, un modèle d'électrode à potentiel constant a été implémenté dans MDFT. Les profils d'énergie libre d'adsorption de l'ion de lithium solvaté dans l'eau sur une électrode en graphite est étudié sur la base du développement. Il a été constaté que, en incluant les effets du solvant de l'eau, le minimum d'énergie obtenu dans le calcul en phase gazeuse disparaît. Les résultats de cette thèse ouvrent la voie à l'étude de des réactions électrochimiques réalistes de transfert d'électrons d'une large gamme de systèmes en utilisant la MDFT.Developments and verification of molecular density functional theory (MDFT) is done in this thesis for the purpose of studying realistic electrochemical electron transfer reactions. Precise predictions of the electron transfer properties at electrochemical interfaces using MDFT require the application of pressure correction methods. The correctness of the two pressure correction strategies to MDFT proposed in the literature has been examined in the context of electron transfer. It has been shown that only those correction methods that respect the variational principle can be used for studying electron transfer. On the other hand, we shown that MDFT reproduces very well the results of solvation structure and electron transfer properties of quinones solvated in acetonitrile (MeCN) that are calculated with molecular dynamics (MD) simulations using much more sophisticated force fields. We then take advantage of the numerical efficiency of MDFT to calculate the reorganization free energies of numerous 1,4-benzoquinone (BQ) derivatives. We found that the electron transfer of all the BQ derivatives solvated in MeCN can be well described by Marcus theory. Finally, a constant potential electrode model has been implemented in MDFT. The adsorption free energy profiles of lithium ion solvated in water on a graphite electrode is studied based on the development. It has be found that, upon including the water solvent effects, the energy minimum obtained in gas phase calculation disappears. The results of this thesis pave the wave for studying realistic electrochemical electron transfer reactions of a wide range of systems using MDFT
Potentiels d'apprentissage automatique pour la simulation des électrolytes de batteries à ions fluorure
No full textLes batteries à ions fluorure (FIB) représentent une technologie prometteuse post-Li-ion, mais l'identification d'électrolytes avec une haute mobilité des ions fluorure à température ambiante demeure un défi majeur. En effet, la recherche dans ce domaine est freinée par une compréhension limitée du mécanisme de conduction des ions fluorure. Dans ce manuscrit de thèse, je présenterai mon travail sur l'utilisation des dynamiques moléculaires basées sur un potentiel d'apprentissage automatique (MLP) pour comprendre le mécanisme de diffusion ionique dans les électrolytes solides et liquides. En particulier, nous utiliserons le BaSnF4 comme électrolyte solide de référence pour comprendre comment les ions Sn2+ déterminent de manière critique le mouvement des ions F-. À la suite de travaux antérieurs, nous avons conçu un électrolyte à haute entropie, où le Np1F/ACN et le CsF/H2O sont mélangés, pour explorer des électrolytes liquides potentiels avec une haute mobilité des ions F-.Dans le chapitre 3, nous nous concentrerons sur la précision et l'efficacité de la méthode MLP comparée aux potentiels d'interaction classiques et aux dynamiques moléculaires ab initio. Le MLP a émergé comme une méthode prometteuse pour approcher la surface d'énergie potentielle avec une grande précision et efficacité. Cependant, la polyvalence et l'efficacité d'une telle méthode par rapport aux potentiels d'interaction classiques sont rarement étudiées. En utilisant le BaSnF4 et un système auxiliaire plus simple, NaF, qui possède une structure de type sel gemme, nous montrons comment un MLP peut capturer les interactions subtiles des paires solitaires de Sn, tandis qu'un champ de force polarisable échoue. La précision de notre MLP est validée en comparant les propriétés vibrationnelles telles que la dispersion des phonons et les équations d'état avec les résultats obtenus par la théorie de la fonctionnelle de la densité, et elle montre un excellent accord avec cette théorie. Le MLP présente également une efficacité computationnelle nettement améliorée par rapport à la méthode de dynamiques moléculaires ab initio de référence.Dans le chapitre 4, nous fournirons une investigation complète du comportement de diffusion des ions F⁻ pour le BaSnF4, qui présente une haute conductivité ionique de 1×10-4 S/cm à température ambiante, mais dont le mécanisme de conduction ionique sous-jacent et les implications des paires solitaires (LP) de Sn2+ dans ce processus restent obscurs. En utilisant les dynamiques moléculaires basées sur l'apprentissage automatique, nous avons étudié comment le mouvement des différentes espèces affecte le paysage énergétique de diffusion. Nous avons démontré que les ions Sn2+ jouent un rôle fondamental. Leur mouvement translationnel conduit à un canal de conduction ionique avec un rayon plus large, augmentant ainsi la conductivité ionique du BaSnF4. Cela modifie également la dynamique d'orientation des LP. En outre, nous avons examiné de manière exhaustive le comportement de diffusion des ions fluorure dans le BaSnF4 et confirmé une diffusion bidimensionnelle au sein des couches Ba-Sn, tandis que dans l'autre direction, les ions F- traversent rapidement la couche Sn-Sn, créant des défauts de Frenkel dans la structure. Notre travail élucide le mécanisme atomistique régissant la conduction des ions fluorure dans les conducteurs ioniques rapides et contribuera à la conception rationnelle des électrolytes solides pour les FIB.Dans le chapitre 5, nous présenterons nos premières tentatives sur les électrolytes liquides mixtes. Les propriétés prometteuses des solutions isolées de Np1F/ACN et CsF/H2O ainsi que les avantages tirés du système à haute entropie rendent le mélange intéressant. Dans ce travail, nous avons d'abord entraîné le MLP pour le mélange et validé notre MLP par rapport aux résultats calculés par la DFT. Nous avons ensuite réalisé des dynamiques moléculaires à grande échelle et analysé le comportement des ions F-.Fluoride ion batteries (FIBs) are a promising post-Li-ion battery technology, but identifying electrolytes with high room temperature fluoride ion mobility remains a significant hurdle. Indeed, the research in this field is hindered by a limited understanding of the fluoride ion conduction mechanism. In this thesis manuscript, I will present my work on using machine learning potential (MLP) based molecular dynamics to understand the ionic diffusion mechanism in solid and liquid electrolytes. In particular, we will use BaSnF4 as a reference solid electrolyte to understand how Sn2+ ions critically determine the F- ionic motion. Following previous work, we designed the high-entropy electrolyte, where Np1F/ACN and CsF/H2O are mixed, to explore liquid electrolyte with high F- ion mobility.In Chapter 3, we will focus on the accuracy and efficiency of the MLP method compared to classical interaction potential and ab initio molecular dynamics. MLP has emerged as a promising method to approach the potential energy surface with high accuracy and efficiency. However, the versatility and efficiency of such a method compared with classical interaction potential are rarely investigated. Using BaSnF4 and an auxiliary simpler system NaF, which holds a rock salt structure, we show how an MLP can capture the subtle interactions of Sn lone pairs (LPs) while a polarizable force field fails. The accuracy of our MLP is validated by comparing vibrational properties such as phonon dispersion and equation of states with the results obtained from density functional theory and it demonstrates excellent agreement with density functional theory. The MLP also exhibits significantly boosted computational efficiency compared with the reference ab initio molecular dynamics method.In Chapter 4, we will provide a comprehensive investigation of the F- ion diffusion behavior for BaSnF4, which exhibits a high ionic conductivity of 110-4 S/cm at ambient temperature, but the underlying ionic conduction mechanism for BaSnF4 and the involvements of Sn2+ LPs in this process remain obscure. Using machine learning molecular dynamics, we investigated how the motion of the various species affects the diffusion energy landscape. We demonstrated that the Sn2+ ions play a fundamental role. Their translational motion leads to an ionic conduction channel with a larger radius, thereby increasing BaSnF4 ionic conductivity. It also alters the LPs orientational dynamics. Furthermore, we comprehensively examined the fluoride ion diffusion behavior in BaSnF4 and confirmed two-dimensional diffusion within the Ba-Sn layers, while on the other direction, the F- ions rapidly cross the Sn-Sn layer, creating Frenkel defects in the structure. Our work elucidates the atomistic mechanism governing the fluoride ion conduction in fast ionic conductors and will contribute to the rational design of FIBs solid electrolytes.In Chapter 5, we will present our initial attempts at mixed liquid electrolytes. The promising properties of isolated Np1F/ACN and CsF/H2O solutions as well as the benefits gained from the high entropy system make the mixture an interesting system. In this work, we first trained the MLP for the mixture and validated our MLP against DFT-computed results. We then performed large-scale molecular dynamics and analyzed the F- ion behavior
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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