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Thematische Bibliographien / Kinetic modelling, density functional theory (DFT) / Zeitschriftenartikel

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Zeitschriftenartikel zum Thema „Kinetic modelling, density functional theory (DFT)“

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Veröffentlicht am 29. März 2025

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1

Sibanda, David, Sunday Temitope Oyinbo und Tien-Chien Jen. „A review of atomic layer deposition modelling and simulation methodologies: Density functional theory and molecular dynamics“. Nanotechnology Reviews 11, Nr. 1 (01.01.2022): 1332–63. http://dx.doi.org/10.1515/ntrev-2022-0084.

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Abstract The use of computational modelling and simulation methodologies has grown in recent years as researchers try to understand the atomic layer deposition (ALD) process and create new microstructures and nanostructures. This review article explains and simplifies two simulation methodologies, molecular dynamics and the density functional theory (DFT), in solving atomic layer deposition problems computationally. We believe that these simulation methodologies are powerful tools that can be utilised in atomic layer deposition. DFT is used to solve problems in surface science and catalysis (predicting surface energy, adsorption energy, charge transfer, etc.), semiconductors (band structure, defect bands, band gap, etc.), superconductors (electron–phonon coupling, critical transition temperature), and molecular electronics (conductance, current–voltage characteristics). Molecular dynamics (MD) is used to predict the kinetic and thermodynamic properties of a material. Of interest in this article is a review where different material problems emanating from atomic layer deposition from these fields have been addressed by DFT and MD. Selected publications are discussed where DFT and MD have been successfully applied in atomic layer deposition (and related processes in some instances). The applications of DFT stretch from binding energy calculations of molecules and the solid band structure in chemistry and physics, respectively, computing the electron density up to determining the properties of a many-electron system. Also highlighted in this review study are the challenges that DFT and MD simulations must overcome.

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Žula, Matej, Miha Grilc, Andrii Kostyniuk, Giorgio Tofani, Edita Jasiukaitytė-Grojzdek, Tina Ročnik Kozmelj, Ramesh Kumar Chowdari et al. „Biorefining Twin Transition: Digitalisation for Bio-based Chemicals/Materials - Discovery, Design and Optimisation“. CHIMIA 77, Nr. 12 (20.12.2023): 816–26. http://dx.doi.org/10.2533/chimia.2023.816.

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The article discusses the production of platform chemicals from various biological sources, including glycerol, lignin, cellulose, bio-oils, and sea products. It presents the results of catalytic and downstream processes involved in the conversion of these biomass-derived feedstocks. The experimental approaches are complemented by numerical descriptions, ranging from density functional theory (DFT) calculations to kinetic modellingof the experimental data. This multi-scale modelling approach helps to understand the underlying mechanisms and optimize the production of platform chemicals from renewable resources.

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Taifan, William, Adam A. Arvidsson, Eric Nelson, Anders Hellman und Jonas Baltrusaitis. „CH4 and H2S reforming to CH3SH and H2 catalyzed by metal-promoted Mo6S8 clusters: a first-principles micro-kinetic study“. Catalysis Science & Technology 7, Nr. 16 (2017): 3546–54. http://dx.doi.org/10.1039/c7cy00857k.

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Density Functional Theory (DFT) and microkinetic modelling of CH₄ and H₂S reactions to form CH₃SH and H₂ as a first step in elucidating complex pathways in oxygen-free sour gas reforming was performed.

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Krayovskyy, Volodymyr, Volodymyr Pashkevych, Andriy Horpenuk, Volodymyr Romaka, Yuriy Stadnyk, Lyubov Romaka, Andriy Horyn und Vitaliy Romaka. „RESEARCH OF THERMOMETRIC MATERIAL Er1-xScxNiSb. I. MODELLING OF PERFORMANCES“. Measuring Equipment and Metrology 82, Nr. 2 (2021): 16–21. http://dx.doi.org/10.23939/istcmtm2021.02.016.

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Automated The results of modeling performances of the semiconductor solid solution Er1-xScxNiSb are presented, which can be a promising thermometric material for the manufacture of sensitive elements of thermoelectric and electroresistive thermocouples. Fullprof Suite software was used to model the crystallographic characteristics of the Er1-xScxNiSb thermometric material. Modeling of the electronic structure of Er1-xScxNiSb was performed by Coring-Kon-Rostocker methods in the approximation of coherent potential and local density using the exchange-correlation potential Moruzzi-Janak-Williams and Linear Muffin-Tin Orbital in the framework of DFT density functional theory. The Brillouin zone was divided into 1000 k-points, which were used to model energetic performances by calculating DOS. The width of the energy window was 22 eV and was chosen to capture all semi-core states of p-elements. Full potential (FP) was used in the representation of the linear MT orbital in the representation of plane waves. The accuracy of calculating the position of the Fermi level was εF ± 6 meV. To verify the existence of a continuous solid solution, Er1-xScxNiSb substitution, the change in the values of the period of the unit cell a (x) was calculated within the framework of the DFT density functional theory in the range x = 0–1.0. It is presented that the calculated and experimentally obtained dependences of the period of the unit cell a(x) Er1-xScxNiSb are almost parallel, which confirms the correctness of the used tools and the obtained modeling results. To research the possibility of obtaining thermometric material Er1-xScxNiSb in the form of a continuous solid solution was performed modeling of thermodynamic calculations in the approximation of harmonic oscillations of atoms in the theory of DFT density functional for a hypothetical solid solution Er1-xScxNiSb, x = 0–1.0. It is shown that the change in the values of free energy ΔG(x) (Helmholtz potential) passes through the minimum at the concentration x≈0.1 for all temperatures of possible homogenizing annealing of the samples, indicating the solubility limit of Sc atoms in the structure of the ErNiSb compound. The presence of this minimum indicates that the substitution of Er atoms for Sc atoms in the ErNiSb compound is energetically advantageous only up to the concentration of impurity atoms Sc, x≈0.1. At higher concentrations of Sc atoms, x> 0.10, stratification occurs (spinoidal phase decay). It is shown that modeling of the mixing entropy behavior S even at a hypothetical temperature T = 4000 K shows the absence of complete solubility of Sc atoms in Er1-xScxNiSb. To model the energetic and kinetic performances of the semiconductor thermometric material Er1-xScxNiSb, particularly the behavior of the Fermi level F e , bandgap width g e the distribution of the density of electronic states (DOS) and the behavior of its electrical resistance ρ(x, T) is calculated for an ordered variant of the structure in which the Er atoms in position 4a are replaced by Sc atoms. It is shown that the ErNiSb compound is a semiconductor of the electronic conductivity type, in which the Fermi level is located near the level of the conduction band C e . The modeling showed that at higher concentrations of Sc atoms, the number of generated acceptors exceeds the concentration of uncontrolled donors, and the concentration of free holes exceeds the concentration of electrons. Under these conditions, the Fermi level F e approaches, and then the level of the valence band Er1- xScxNiSb crosses: the dielectric-metal conductivity transition occurs. The experiment should change the sign of the thermo-emf coefficient α(x, T) Er1-xScxNiSb from negative to positive, and the intersection of the Fermi level F e and the valence band changes the conductivity from activating to metallic: on the dependences ln(ρ(1/T)) the activation sites disappear, and the values of resistivity ρ increase with temperature.

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Miran, Hussein A., Mohammednoor Altarawneh, Zainab N. Jaf, M. Mahbubur Rahman, Mansour H. Almatarneh und Zhong-Tao Jiang. „Influence of the variation in the Hubbard parameter (U) on activation energies of CeO2-catalysed reactions“. Canadian Journal of Physics 98, Nr. 4 (April 2020): 385–89. http://dx.doi.org/10.1139/cjp-2019-0065.

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Accurate description of thermodynamic, structural, and electronic properties for bulk and surfaces of ceria (CeO2) necessitates the inclusion of the Hubbard parameter (U) in the density functional theory (DFT) calculations to precisely account for the strongly correlated 4f electrons. Such treatment is a daunting task when attempting to draw a potential energy surface for CeO2-catalyzed reaction. This is due to the inconsistent change in thermo-kinetics parameters of the reaction in reference to the variation in the U values. As an illustrative example, we investigate herein the discrepancy in activation and reaction energies for steps underlying the partial and full hydrogenation of acetylene over the CeO2(111) surface. Overall, we find that both activation and reaction energies positively correlate with the increase in the U value. In addition to benchmarking against more accurate theoretical methodologies, we suggest that U values are better optimized against kinetics modelling of experimentally observed profiles of products from the catalytic-assisted system of reactions.

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Dogru Mert, Basak, Mehmet Erman Mert, Gülfeza Kardas und Birgül Yazici. „The experimental and quantum chemical investigation for two isomeric compounds as aminopyrazine and 2-amino-pyrimidine against mild steel corrosion“. Anti-Corrosion Methods and Materials 63, Nr. 5 (2016): 369–76. http://dx.doi.org/10.1108/acmm-12-2014-1480.

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Purpose The purpose of this paper is to investigate the adsorption and corrosion inhibition of two isomeric compounds (C4H5N3) as aminopyrazine (AP) and 2-amino-pyrimidine (2AP) on mild steel (MS) in 0.5 M HCl. The study was a trial to combine experimental and modelling studies and research effect of molecular geometry on inhibition effect of inhibitor molecules. Design/methodology/approach The thermodynamic, kinetic and quantum parameters were determined. The electrochemical impedance spectroscopy and anodic polarisation measurements were obtained. The scanning electron microscope was used for monitoring electrode surface. The highest occupied molecular orbital, energy of the lowest unoccupied molecular orbital, Mulliken and natural bonding orbital charges on the backbone atoms, absolute electronegativity, absolute hardness were calculated by density functional theory (DFT)/B3LYP/6-311G (++ d,p). Findings Results showed that AP and 2AP suppressed the corrosion rate of MS. The corrosion current values were 0.530, 0.050 and 0.016 mA cm-2 in HCl, AP and 2AP containing HCl solutions, respectively. It was illustrated with the blocked fraction of the MS surface by adsorption of inhibitors which obeyed the Langmuir isotherm. The inhibition efficiency follows the order: 2AP > AP which is in agreement with experimental and quantum results. Originality/value This paper provides lay a bridge on the molecular geometry and inhibition efficiency by electrochemical tests and modelling study. The inhibition effect of AP and 2AP has not been compared with each other, neither experimentally nor theoretically. This study put forward possible application of 2AP as corrosion inhibitor especially for closed-circuit systems.

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Wang, Ying, und Daniel John Blackwood. „Exploring the Kinetics of Oxygen Reduction Reaction in Relation to Pitting Corrosion Resistance in Fe-Cr Alloys“. ECS Meeting Abstracts MA2024-01, Nr. 18 (09.08.2024): 1241. http://dx.doi.org/10.1149/ma2024-01181241mtgabs.

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Pitting corrosion, a major concern in materials science and engineering, threatens critical metallic structures and components. Its implications reach across daily life and industries such as energy, transportation, and infrastructure, potentially causing environmental harm, economic losses, and even loss of life. This complex process is influenced by factors including material composition, local environment, and mechanical stresses.1 Once initiated, pit propagation rates are largely dependent on the magnitude of the supporting cathodic current available from the oxygen reduction reaction (ORR) occurring on the external passive film.2 In Fe-Cr alloys, the ORR occurs on this film, undergoing a mixed diffusion and kinetic-controlled process. The number of electrons involved and the corrosion rate are determined by the thermodynamically stable state of the passive film. This research studies the ORR kinetics on FeCr alloys fabricated by arc-melting, using both computational and experimental methods. The rotating disc electrode technique was employed across various Fe:Cr alloys in alkaline and neutral electrolytes. The Koutecky-Levich analysis showed a dominant four-electron ORR pathway in all tested Fe-Cr alloys, with the ORR significantly inhibited by higher proportions of Cr2O3 in the film, suggesting a correlation with high chromium content. Experimental ORR overpotentials, when combined with theoretical potential-pH (Pourbaix) diagrams, helped discern the likely characteristics of the passive films on the alloys. It was deduced that the catalytic properties of potential passive films increased in the order Cr2O3 < Fe3O4 < Fe2O3 < FeCr2O4. These findings, excellently aligned with density functional theory (DFT) modelling, underscore the role of increased chromium levels in slowing pitting progression by suppressing the ORR. In summary, this research offers distinctive insights into the correlation between the kinetics of the ORR and the resistance to localized corrosion in Fe-Cr alloys, which enhances our understanding of the underlying mechanisms of pitting corrosion. Keywords FeCr alloy, pitting corrosion, ORR, rotating disc electrode, DFT Reference [1] B. Zhang, J. Wang, B. Wu, X. W. Guo, Y. J. Wang, D. Chen, Y. C. Zhang, K. Du, E. E. Oguzie, and X. L. Ma, Nat. Commun. (2018) 9, 2559. [2] G. T. Burstein, P. C. Pistorius, and S. P. Mattin, Corros. Sci. (1993) 35, 57.

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Jaberi, Ali, Michel L. Trudeau, Jun Song und Raynald Gauvin. „On the Study of Lithium Diffusivity in Lithium Nickel Manganese Cobalt Oxide Cathodes“. ECS Meeting Abstracts MA2022-01, Nr. 2 (07.07.2022): 381. http://dx.doi.org/10.1149/ma2022-012381mtgabs.

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Climate change, population growth, and rising fossil fuel prices have encouraged governments and scientists for alternate energy resources. This energy transition requires a high-performance energy storage device to satisfy the high energy and power demand and lithium-ion battery (LIB) is one of the promising one. The performance of these batteries ultimately relies on the properties of their components. In this regard, to meet the high-power demand in high-power applications (such as electric vehicles (EVs) and hybrid EVs), materials with rapid lithium transport are required. Lithium Nickel Manganese Cobalt Oxide (NMC) has attracted scientists’ attentions due to its outstanding performance as a cathode material. Therefore, understanding the effect of various factors on lithium diffusivity in NMC is critical to develop high-performance LIBs for high-power applications. Electrochemical methods such as potentiostatic and galvanostatic intermittent titration techniques (PITT and GITT) have been frequently utilized to experimentally quantify lithium diffusivity in NMC. These techniques need the knowledge of electrode particle shape and dimension, and uncertainty about these parameters leads to substantial errors in predicting the diffusion coefficient. In addition, because these techniques consider the response of the whole electrochemical cell, it is hard to distinguish the effect of different structural factors on Li diffusivity in a single NMC active material. Therefore, an appropriate method still needs to be developed to capture the structural effects on lithium diffusivity in NMC. For this purpose, a multi-level modelling from Density Functional Theory (DFT) to kinetic Monte Carlo (KMC) should be implemented. In this study, we will use DFT to find the ground state energy of NMC at different lithium concentrations and configurations. Also, the minimum energy path of lithium migration and the related activation barrier will be found by Climbing Image-Nudge Elastic Band (CI-NEB) method. Then by implementing the configurational dependent activation barrier into the KMC simulation, the lithium diffusivity will be studied. This atomistic simulation gives insight about the structural effects on lithium diffusivity in NMC to further develop this cathode material for high performance LIBs.

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Luisier, Mathieu, Jan Aeschlimann, Jonathan Backman, Jiang Cao, Manasa Kaniselvan, Youseung Lee und Marko Mladenovic. „(Invited) Advanced Modeling of Nanoscale Devices“. ECS Meeting Abstracts MA2023-01, Nr. 33 (28.08.2023): 1849. http://dx.doi.org/10.1149/ma2023-01331849mtgabs.

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Moore’s scaling law has survived during more than 50 years because the transistor fabrication recipes have been continuously adapted and technology boosters have been gradually introduced, e.g. strain, high- dielectrics, or 3-D FinFETs. The driving force behind these innovations has always been the intuition of clever researchers who benefited from classical technology computer aided design (TCAD) tools. The latter have been used in the semiconductor industry since the end of the 1970’s, when the first 2-D simulations of CMOS devices became feasible on a supercomputer [1]. Over the last 40 years, transistors have undergone tremendous evolutions, their dimensions being reduced by several orders of magnitude, while the physical models at the core of commercially available device simulators have remained the same: electron transport is still described by classical drift-diffusion (DD) equations, which have been modified to capture parts of the quantum mechanical effects affecting nano-transistors, e.g. geometrical confinement tunnelling leakages, or energy quantization [2]. A new generation of advanced TCAD tools that go beyond the DD equations and rely on atomistic quantum mechanical concepts is needed to reproduce the characteristics of today’s nanostructures and to predict the performance of not-yet-fabricated components. Such tools should combine different modelling approaches to be able to treat various device types, from state-of-the-art nano-transistors to photo-detectors based on two-dimensional materials or resistive switching random access memories. For example, to shed light on the behaviour of valence change memory (VCM) cells, which consist of metal-insulator-metal stacks, molecular dynamics (MD), kinetic Monte Carlo (KMC), density functional theory (DFT), and quantum transport (QT) should be allied, as illustrated in the accompanying figure. By doing so, the growth of nano-filaments through realistic oxides embedded between two metallic electrodes can be accurately simulated and the electrical current flowing through computed with, e.g., the Non-equilibrium Green’s Function (NEGF) formalism [3]. In this presentation the multi-method simulation environment shown the accompanying Figure will be briefly reviewed. The main focus will be set on the discussion of few applications, among them transistors and memory cells. References: [1] S. Selberherr, W. Fichtner, and H.W. Potzl, “Minimos - A program package to facilitate MOS device design and analysis”, Proceedings of NASECODE I, 275 (1979). [2] A. Wettstein, A. Schenk, and W. Fichtner, “Quantum device-simulation with the density-gradient model on unstructured grids”, IEEE Trans. On Elec. Dev. 48, 279 (2001). [3] M. Kaniselvan, M. Luisier, and M. Mladenovic, “An Atomistic Modelling Framework for Valence Change Memory Cells”, Solid-State Electronics 199, 108506 (2023). Figure Caption: Multi-method simulation framework dedicated to the investigation of resistive switching devices, here valence change memory (VCM) cells. First, oxide samples with a low defect concentration are constructed withclassical molecular dynamics (MD) using a melt-and-quench procedure. They arethentransferredto akinetic Monte Carlo (KMC) solver that determines the distribution of oxygen vacancies (VO,green spheres) within the oxide layer. All input parameters to KMC (diffusioncoefficients and generation/recombination rates) are computed with density functional theory(DFT), which is also used to calculate the Hamiltonian (H) and Overlap (S) matrices of the created VCM structure. Finally, these quantities are passed to aquantum transport (QT) tool to perform ab initiodevice simulations. Figure 1

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Homma, Takayuki, Masahiro Kunimoto und Masahiro Yanagisawa. „(Invited) Approaches for Mechanistic Understanding of Electrodeposition Processes for Fabricating Micro/Nano Structures and Devices“. ECS Meeting Abstracts MA2023-01, Nr. 27 (28.08.2023): 1757. http://dx.doi.org/10.1149/ma2023-01271757mtgabs.

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Electrochemical deposition processes have precise controllability, selectivity and uniformity, and have been widely applied for fabricating various functional micro/nano structures and devices. In order to achieve further higher controllability for developing reliable process for manufacturing, molecular-level understanding of the deposition processes is required. Furthermore, this can be be also utilized to understand various applications such as the electrode processes of secondary batteries using metal anodes and so on. For this, we have attempted to apply theoretical approaches such as density functional theory (DFT) and kinetic Monte Carlo (KMC) calculations[1.2], as well as experimental methods such as surface enhanced Raman microscopy equipped with plasmonic sensors[3-5]. In this paper, these approaches with some of the resent results will be described. The analysis using DFT calculations provided the molecular-level insights for the catalytic activity of the electroless deposition reaction process at the surface, with the effects of the additive species and solvation. Also, in combination with the KMC calculation, multi-scale simulation for the nucleation and growth process at the Zn anode surface for the secondary battery was attempted. While these approaches enable quantitative discussion for the mechanistic understanding of the processes, we also attempted to obtain "real" data from experimental approaches. For this, we applied surface enhanced Raman scattering (SERS) and developed "plasmonic sensors" with controlled nanostructures to obtain high signal enhancement at electrode-electrolyte interface. We have developed two types of the plasmonic sensors which could achieve extremely high sensitivity. Multi-confocal type SERS microscopy was also developed for mapping and imaging analyses of the electrode surface as well as local pH distributions. By using these techniques, various processes at the electrode surfaces and interfaces have been investigated and modelling of the processes has been carried out. This work was financially supported in part by “Development of Systems and Technology for Advanced Measurement and Analysis” program from Japan Science and Technology Agency, and Grant-in-Aid for Scientific Research, MEXT, Japan. [1] Y. Onabuta, M. Kunimoto, H. Nakai, T. Homma, Electrochim. Acta, 307, 536 (2019). [2] Y. Onabuta, M. Kunimoto, S. Wang, Y. Fukunaka, H. Nakai, T. Homma, J. Electrochem. Soc., 169, 092504 (2022). [3] M. Yanagisawa, M. Saito, M. Kunimoto, T. Homma, Appl. Phys. Express, 9 , 122002 (2016). [4] M. Kunimoto, F. Yamaguchi, M. Yanagisawa, T. Homma, J. Electrochem. Soc., 166, D212 (2019). [5] T. Wang, M. Kunimoto, M. Yanagisawa, M. Morita, T. Abe, T. Homma, Energy Env. Mat., in press (2022).

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Shluger, Alexander. „(Invited) An Interplay between Electronic and Ionic Processes in Oxide Resistive Switching Devices“. ECS Meeting Abstracts MA2024-01, Nr. 57 (09.08.2024): 3017. http://dx.doi.org/10.1149/ma2024-01573017mtgabs.

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Emerging memory devices play a major role in implementing artificial neural networks as basic types of neuromorphic hardware. They provide extra functionality to conventional CMOS technology, such as the ability to implement non-volatile memory within a nanoscale region on the chip. Among 2-terminal devices, the resistive switching random access memory (RRAM) devices are very promising for these applications. However, the mechanisms of resistance changes depend on the oxide and metal electrode material and are still debated. Under an applied stress bias, MIM devices experience changes in their resistance from relatively large, in the high resistance state (HRS), to relatively low, in the low resistance state (LRS). These effects have generally been attributed to defect generation and aggregation in the oxide and depend on the chemical nature of metal electrodes. Using multiscale modelling, we investigate the role of electron injection and hydrogen incorporation inside amorphous (a) oxide films of SiO2, HfO2, Al2O3 and at interfaces with Si and TiN electrodes in creation of new defects, oxide degradation, and resistance change. The initial models of a-SiO2, a-HfO2 and a-Al2O3 structures are created using classical force-fields and the LAMMPS package. The volume and geometry of all structures are fully optimized using density functional theory (DFT) implemented in the CP2K code with the range-separated hybrid PBE0-TC-LRC functional, as described in detail in [1]. The results demonstrate that hole injection into amorphous SiO2, HfO2 and Al2O3 leads to hole localization at low-coordinated O sites in the amorphous network [2]. Injected extra electrons localize in amorphous SiO2 and HfO2 in deep states about 3.0 eV below the mobility edge [2]. Trapping of up to two electrons at intrinsic sites results in weakening of Si-O and Hf-O bonds and emergence of efficient bond breaking pathways for producing neutral O vacancies and interstitial Oi 2- ions with low activation barriers [2]. These barriers as well as barriers for migration of the O2- ion (< 0.5 eV) are further reduced by bias application. Simulations of SiO2/TiN interfaces [3] explain how, as a result of electroforming, the system undergoes very significant structural changes with the oxide being significantly reduced, interface being oxidized, and part of the oxygen leaving the system. Creation of O vacancies facilitates trap-assisted tunnelling through oxide films and is responsible for oxide charging and leakage current. Hydrogen and metal incorporation from metal electrodes leads to creation of additional defects in the oxide. DFT calculations of the incorporation and diffusion of Ag in Ag/SiO2/Me (Me=W or Pt) RRAM devices [4] show how the interplay between Ag+ ion diffusion, electron injection and vacancy creation lead to the formation of Ag clusters and filaments. Atomistic simulations of defect creation in amorphous oxide films are combined with kinetic simulations of trap assisted tunnelling of electrons and ionic diffusion through oxide [5,6]. They provide the mechanisms and time evolution of oxide charging and degradation. These mechanisms are used to simulate the kinetics of dielectric breakdown in devices and explain the mechanisms of set and reset in RRAM devices. [1] A-M. El-Sayed et al., Phys, Rev. B89, 125201 (2014) [2] J. Strand et al., J. Phys.: Condens. Matter30,233001 (2018) [3] J. Cottom et al. ACS Appl. Mater. Interfaces 11, 36232 (2019) [4] K. Patel et al. Microel. Reliab. 98, 144 (2019) [5] A. Padovani et al., J. Appl. Phys. 121, 155101 (2017) [6] J. Strand et al. J. Appl. Phys. 131, 234501 (2022)

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Mostafanejad, Mohammad, Jessica Haney und A. Eugene DePrince. „Kinetic-energy-based error quantification in Kohn–Sham density functional theory“. Physical Chemistry Chemical Physics 21, Nr. 48 (2019): 26492–501. http://dx.doi.org/10.1039/c9cp04595c.

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Urso, Vittoria. „New Functional Orbital-free Within DFT for Metallic Systems“. International Journal of Systems Science and Applied Mathematics 9, Nr. 2 (04.08.2024): 30–36. http://dx.doi.org/10.11648/j.ijssam.20240902.12.

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I present the continuation of a study on Laplacian Level Kinetic Energy (KE) functionals applied to metallic nanosystems. The development of novel Kinetic Energy functionals is an important topic in density functional theory (DFT). The nanoparticles are patterned using gelatin spheres of different sizes, background density and number of electrons. To reproduce the correct kinetic and potential energy density of the various nanoparticles, the use of semilocal descriptors is necessary. Need an explicit density functional expression for the kinetic energy of electrons, including the first e second functional derivative, i.e. the kinetic potential and the kinetic kernel, respectively. The exact explicit form of the non interacting kinetic energy, as a functional of the electron density, is known only for the homogeneous electron gas (HEG), i.e., the Thomas-Fermi (TF) local functional and for 1 and 2 electron systems, i.e., the von Weizsacker (VW) functional. In between these two extreme cases, different semilocal or non local approximations were developed in recent years. Most semilocal KE functionals are based on modifications of the second-order gradient expansion (GE2) or fourth-order gradient expansion (GE4). I find that the Laplacian contribute is fundamental for the description of the energy and the potential of nanoparticles. I propose a new LAP2 semilocal functional which, better than the previous ones, allows us to obtain fewer errors both of energy and potential. More details of the previous calculations can be found in my 2 previous works which will be cited in the text.

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Sieffert, Nicolas, Amol Thakkar und Michael Bühl. „Modelling uranyl chemistry in liquid ammonia from density functional theory“. Chemical Communications 54, Nr. 74 (2018): 10431–34. http://dx.doi.org/10.1039/c8cc05382k.

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We developed a computationally-efficient protocol based on Density Functional Theory (DFT) and a continuum solvation model (CSM) to predict reaction free energies of complexation reactions of uranyl in liquid ammonia.

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Wilbraham, Liam, François-Xavier Coudert und Ilaria Ciofini. „Modelling photophysical properties of metal–organic frameworks: a density functional theory based approach“. Physical Chemistry Chemical Physics 18, Nr. 36 (2016): 25176–82. http://dx.doi.org/10.1039/c6cp04056j.

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Angioletti-Uberti, Stefano, Matthias Ballauff und Joachim Dzubiella. „Dynamic density functional theory of protein adsorption on polymer-coated nanoparticles“. Soft Matter 10, Nr. 40 (2014): 7932–45. http://dx.doi.org/10.1039/c4sm01170h.

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Zhao, Yan, und Shengli Zou. „Mechanism and kinetic properties for the gas-phase ozonolysis of β-ionone“. RSC Advances 6, Nr. 115 (2016): 114256–63. http://dx.doi.org/10.1039/c6ra24630c.

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Choi, Youngwon, Zhihua Dong, Wei Li, Raquel Lizárraga, Se-Kyun Kwon und Levente Vitos. „Density Functional Theory Description of Paramagnetic Hexagonal Close-Packed Iron“. Materials 15, Nr. 4 (09.02.2022): 1276. http://dx.doi.org/10.3390/ma15041276.

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The hexagonal close-packed (hcp) phase of iron is unstable under ambient conditions. The limited amount of existing experimental data for this system has been obtained by extrapolating the parameters of hcp Fe–Mn alloys to pure Fe. On the theory side, most density functional theory (DFT) studies on hcp Fe have considered non-magnetic or ferromagnetic states, both having limited relevance in view of the current understanding of the system. Here, we investigate the equilibrium properties of paramagnetic hcp Fe using DFT modelling in combination with alloy theory. We show that the theoretical equilibrium c/a and the equation of state of hcp Fe become consistent with the experimental values when the magnetic disorder is properly accounted for. Longitudinal spin fluctuation effects further improve the theoretical description. The present study provides useful data on hcp Fe at ambient and hydrostatic pressure conditions, contributing largely to the development of accurate thermodynamic modelling of Fe-based alloys.

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Chutia, Arunabhiram, Adam Thetford, Michail Stamatakis und C. Richard A. Catlow. „A DFT and KMC based study on the mechanism of the water gas shift reaction on the Pd(100) surface“. Physical Chemistry Chemical Physics 22, Nr. 6 (2020): 3620–32. http://dx.doi.org/10.1039/c9cp05476f.

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20

Leung, Kevin. „DFT modelling of explicit solid–solid interfaces in batteries: methods and challenges“. Physical Chemistry Chemical Physics 22, Nr. 19 (2020): 10412–25. http://dx.doi.org/10.1039/c9cp06485k.

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21

Li, Shi-Jun, und De-Cai Fang. „A DFT kinetic study on 1,3-dipolar cycloaddition reactions in solution“. Physical Chemistry Chemical Physics 18, Nr. 44 (2016): 30815–23. http://dx.doi.org/10.1039/c6cp05190a.

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Several popular density functional theory (DFT) methods have been employed to characterize a series of 1,3-dipolar cycloaddition reactions, including the exploration of reaction mechanisms and the calculations of kinetic parameters.

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22

Knijn, P. J., P. J. M. van Bentum, C. M. Fang, G. J. Bauhuis, G. A. de Wijs und A. P. M. Kentgens. „A multi-nuclear magnetic resonance and density functional theory investigation of epitaxially grown InGaP2“. Physical Chemistry Chemical Physics 18, Nr. 31 (2016): 21296–304. http://dx.doi.org/10.1039/c5cp04593b.

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23

Li, Yan, Ning Liu, Chengna Dai, Ruinian Xu, Bin Wu, Gangqiang Yu und Biaohua Chen. „Mechanistic insight into H2-mediated Ni surface diffusion and deposition to form branched Ni nanocrystals: a theoretical study“. Physical Chemistry Chemical Physics 22, Nr. 41 (2020): 23869–77. http://dx.doi.org/10.1039/d0cp03126g.

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Present work investigates the kinetic role of H₂ during Ni surface diffusion and deposition to generate branched Ni nanostructures by employing density functional theory (DFT) calculations and ab initio molecule dynamic (AIMD) simulations.

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24

Budzelaar, Peter H. M. „Ethene trimerization at CrI/CrIII — A density functional theory (DFT) study“. Canadian Journal of Chemistry 87, Nr. 7 (Juli 2009): 832–37. http://dx.doi.org/10.1139/v09-022.

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Catalytic ethene trimerization at a chromium(I) indolate-AlR2Cl centre has been studied by density functional theory (DFT) methods. The reaction is found to follow the standard metallacycle mechanism. At most stages of the reaction, coordination of Cr to the pyrrole ring of the indolate is preferred. In all 13-e intermediates, coordination of the Al-bound chloride to Cr provides additional stabilization: the chloride behaves as a hemilabile ligand. Benzene is found to compete with ethene for coordination to CrI. The final hexene-forming step involves direct Cβ → Cα′ hydrogen transfer; reductive elimination from a possible (hydride)(hexenyl) intermediate is more difficult. The kinetic isotope effect calculated for the direct hydrogen transfer (4.1) agrees well with the experimental value for a bis(phosphino)amide chromium catalyst. Side products obtained in such systems (methylenecyclopentane, methylcyclopentane) can plausibly be explained through routes not involving any (hydride)(alkyl) reductive elimination. Our results indicate that a CrI/CrIII trimerization cycle is possible for some chromium trimerization catalysts, and also suggest that direct hydrogen transfer is most likely a general feature of trimerization at Cr centres.

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Tetlow, H., D. Curcio, A. Baraldi und L. Kantorovich. „Hydrocarbon decomposition kinetics on the Ir(111) surface“. Physical Chemistry Chemical Physics 20, Nr. 9 (2018): 6083–99. http://dx.doi.org/10.1039/c7cp07526j.

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The kinetics of the thermal decomposition of hydrocarbons on the Ir(111) surface is determined using kinetic Monte Carlo (kMC) and rate equations simulations, both based on the density functional theory (DFT) calculated energy barriers of the involved reaction processes.

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26

Todorović, Milica, David R. Bowler, Michael J. Gillan und Tsuyoshi Miyazaki. „Density-functional theory study of gramicidin A ion channel geometry and electronic properties“. Journal of The Royal Society Interface 10, Nr. 89 (06.12.2013): 20130547. http://dx.doi.org/10.1098/rsif.2013.0547.

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Understanding the mechanisms underlying ion channel function from the atomic-scale requires accurate ab initio modelling as well as careful experiments. Here, we present a density functional theory (DFT) study of the ion channel gramicidin A (gA), whose inner pore conducts only monovalent cations and whose conductance has been shown to depend on the side chains of the amino acids in the channel. We investigate the ground state geometry and electronic properties of the channel in vacuum, focusing on their dependence on the side chains of the amino acids. We find that the side chains affect the ground state geometry, while the electrostatic potential of the pore is independent of the side chains. This study is also in preparation for a full, linear scaling DFT study of gA in a lipid bilayer with surrounding water. We demonstrate that linear scaling DFT methods can accurately model the system with reasonable computational cost. Linear scaling DFT allows ab initio calculations with 10 000–100 000 atoms and beyond, and will be an important new tool for biomolecular simulations.

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Ermilova, Inna, Samuel Stenberg und Alexander P. Lyubartsev. „Quantum chemical and molecular dynamics modelling of hydroxylated polybrominated diphenyl ethers“. Phys. Chem. Chem. Phys. 19, Nr. 41 (2017): 28263–74. http://dx.doi.org/10.1039/c7cp03471g.

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A series of 19 hydroxylated polybrominated diphenyl ethers (OH-PBDEs) have been studied using density functional theory (DFT) and molecular dynamics simulations with the purpose of investigating eventual correlations between their physicochemical properties and toxic action.

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Hao, Zijun, Ling Guo, Minmin Xing und Qian Zhang. „Mechanistic study of ethanol steam reforming on TM–Mo6S8 clusters: a DFT study“. Catalysis Science & Technology 9, Nr. 7 (2019): 1631–43. http://dx.doi.org/10.1039/c8cy02151a.

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The mechanism of ethanol steam reforming (ESR) on TM–Mo₆S₈ (TM = Pt, Pd) clusters is systematically investigated using a combination of the microscopic kinetic model, energetic span model (ESM) and d-band model under density functional theory (DFT) calculations.

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Fristrup, Peter, und Niels Christensen. „Kinetic Isotope Effects (KIE) and Density Functional Theory (DFT): A Match Made in Heaven?“ Synlett 26, Nr. 04 (05.02.2015): 508–13. http://dx.doi.org/10.1055/s-0034-1380097.

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30

de Jong, Flip, Milica Feldt, Jonas Feldt und Jeremy N. Harvey. „Modelling absorption and emission of a meso-aniline–BODIPY based dye with molecular mechanics“. Physical Chemistry Chemical Physics 20, Nr. 21 (2018): 14537–44. http://dx.doi.org/10.1039/c8cp01877d.

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Absorption and emission spectra of 8-(4-dimethylaminophenyl)-1,3,5,7-tetramethyl–BODIPY have been calculated using Coupled Cluster (CC) approaches, Time-Dependent Density Functional Theory (TD-DFT) and a QM-informed MM approach.

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31

Yu, Caoming, Fang Wang, Yunlei Zhang, Leihong Zhao, Botao Teng, Maohong Fan und Xiaona Liu. „H2 Thermal Desorption Spectra on Pt(111): A Density Functional Theory and Kinetic Monte Carlo Simulation Study“. Catalysts 8, Nr. 10 (12.10.2018): 450. http://dx.doi.org/10.3390/catal8100450.

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Theoretical investigation of the static and kinetic behaviors of H and H2 on metal surface plays a key role in the development of hydrogenation catalysts and new materials with high H2 storage capacity. Based on the density functional theory (DFT) calculation of H and H2 adsorption on Pt(111), H(a) adatom strongly interacts with surface Pt; while H2 weakly adsorbs on Pt(111). H(a) adatoms stably occupy the face-centered cubic sites on Pt(111) which agrees with the experimental LERS observations. By using kinetic Monte Carlo (kMC) simulation, the qualitative effects of the kinetic parameters on the H2 TDS spectra indicate that the H2 desorption peaks shift to the low temperature with increasing pre-exponential factor and decreasing desorption barrier. Simultaneously, the desorption peaks shift downwards and broaden to two peaks with the increase of the lateral interaction energy among H(a) adatoms. Using the kMC simulation based on DFT calculation, the predicted H2 TDS spectra are well consistent with the experimental ones. It unanimously proves that the two peaks of TDS spectra are derived from the lateral interactions among H(a). This work provides the intrinsic kinetics of H(a) and H2 on Pt(111) at an atomic level, and gives insight into the development of hydrogenation catalysts.

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Bent, Grace-Anne, Paul Maragh, Tara Dasgupta, Richard A. Fairman und Lebert Grierson. „Kinetic and density functional theory (DFT) studies of in vitro reactions of acrylamide with the thiols: captopril, l-cysteine, and glutathione“. Toxicology Research 4, Nr. 1 (2015): 121–31. http://dx.doi.org/10.1039/c4tx00070f.

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33

Jackson, R. A., und M. E. G. Valerio. „Computer Modelling of Intrinsic Defects and Th Incorporation in MgF₂: What we can Learn from Atomistic Modelling and DFT Approaches“. Journal of Physics: Conference Series 2298, Nr. 1 (01.08.2022): 012002. http://dx.doi.org/10.1088/1742-6596/2298/1/012002.

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Abstract The doping of MgF2 with the 229 isotope of Th is of interest in the development of nuclear clock devices. This paper describes atomistic modelling of MgF2, its intrinsic defects and Th doping, and compares the results with a recent study using Density Functional Theory (DFT).

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34

Bissesar, Shivan, Davita M. E. van Raamsdonk, Dáire J. Gibbons und René M. Williams. „Spin Orbit Coupling in Orthogonal Charge Transfer States: (TD-)DFT of Pyrene—Dimethylaniline“. Molecules 27, Nr. 3 (28.01.2022): 891. http://dx.doi.org/10.3390/molecules27030891.

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The conformational dependence of the matrix element for spin–orbit coupling and of the electronic coupling for charge separation are determined for an electron donor–acceptor system containing a pyrene acceptor and a dimethylaniline donor. Different kinetic and energetic aspects that play a role in the spin–orbit charge transfer intersystem crossing (SOCT-ISC) mechanism are discussed. This includes parameters related to initial charge separation and the charge recombination pathways using the Classical Marcus Theory of electron transfer. The spin–orbit coupling, which plays a significant role in charge recombination to the triplet state, can be probed by (TD)-DFT, using the latter as a tool to understand and predict the SOCT-ISC mechanism. The matrix elements for spin–orbit coupling for acetone and 4-thio-thymine are used for benchmarking. (Time Dependent-) Density Functional Theory (DFT and TD-DFT) calculations are applied using the quantum chemical program Amsterdam Density Functional (ADF).

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35

Bailie, David, Steven White, Rachael Irwin, Cormac Hyland, Richard Warwick, Brendan Kettle, Nicole Breslin et al. „K-Edge Structure in Shock-Compressed Chlorinated Parylene“. Atoms 11, Nr. 10 (18.10.2023): 135. http://dx.doi.org/10.3390/atoms11100135.

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We have carried out a series of experiments to measure the Cl K-absorption edge for shock-compressed samples of chlorinated parylene. Colliding shocks allowed us to compress samples up to four times the initial density with temperatures up to 10 eV. Red shifts in the edge of about 10 eV have been measured. We have compared the measured shifts to analytical modelling using the Stewart–Pyatt model and adaptions of it, combined with estimates of density and temperature based on hydrodynamic modelling. Modelling of the edge position using density functional theory molecular dynamics (DFT-MD) was also used and it was found that good agreement was only achieved when the DFT simulations assumed conditions of lower temperature and slightly higher density than indicated by hydrodynamic simulations using a tabular equation of state.

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36

Zaveri, Jaydev, Shankar Raman Dhanushkodi, Michael W. Fowler, Brant A. Peppley, Dawid Taler, Tomasz Sobota und Jan Taler. „Development of Deep Learning Simulation and Density Functional Theory Framework for Electrocatalyst Layers for PEM Electrolyzers“. Energies 18, Nr. 5 (20.02.2025): 1022. https://doi.org/10.3390/en18051022.

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The electrocatalyst layers (ECLs) in polymer electrolyte membrane (PEM) electrolyzers are fundamentally comprised of IrOx catalysts, support material, and an ionomer. Their stability is critically dependent on structure and composition, necessitating a thorough understanding of ionization potential and work function. We employ Density Functional Theory (DFT) to determine the ionization states of ECLs and to optimize their electronic properties. Furthermore, advanced deep learning simulations (DLSs) significantly enhance the kinetic and transport behaviors of these layers. This work integrates DFT and DLS to elucidate the characteristics of ECLs within PEM electrolyzer cells. We strategically utilize DFT to refine catalyst molecules and assess their electronic properties, while DLS is employed to predict the potential energy of support molecules in the catalyst layers. We establish a clear relationship between the energy and geometry of IrOx molecules. The DFT-DLS framework robustly calculates potential energy and reaction coordinates, effectively bridging theoretical computations with the dynamic behavior of molecules in catalyst layers. We validate our model by comparing it with the experimental polarization curve of the IrOx-based anode catalyst layer in a functioning electrolyzer. The observed Tafel slope and exchange current density unequivocally confirm that the oxygen evolution reaction (OER) occurs through a well-defined electrochemical pathway, with oxygen generation proceeding according to the charge transfer mechanism predicted by the DFT-DLS framework.

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Zhang, Jiawei, und Fei Yan. „Pyrolysis behaviors of polyethylene terephthalate (PET): A density functional study“. International Journal of Modern Physics B 35, Nr. 04 (28.01.2021): 2150048. http://dx.doi.org/10.1142/s021797922150048x.

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In this paper, the pyrolysis mechanism of polyethylene terephthalate (PET), which accounts for a large proportion in plastics component, is investigated by density functional theory (DFT). The dissociation energies of the several important bonds in PET are calculated. The results indicate that the C–C bond between two carboxyl groups in ethylene terephthalate is very weak, followed by the single bond between carboxyl group and carbon atom. The kinetic analysis shows the energy barriers of the reactions to release CO2 are stable while that of CO fluctuates. In addition, the reaction paths of the formation of cyclic compounds are proposed.

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Turebayeva, Pana, Alexey N. Guslyakov, Svetlana A. Novikova, Andrei I. Khlebnikov, Ekaterina A. Befus, Evgeniy P. Meshcheryakov, Abdigali A. Bakibaev et al. „Absorption of Water Vapor by Bambus[6]uril and a Density Functional Theory Study of Its Aqua Complexes“. Molecules 28, Nr. 23 (21.11.2023): 7680. http://dx.doi.org/10.3390/molecules28237680.

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The absorption/desorption of water vapor by bambus[6]uril (Bu[6]) has been studied. According to kinetic experiments, the absorption capacity of Bu[6] is 4 moles of water per 1 mole of Bu[6] with the absorption duration of 20 min and the complete desorption duration of 100 min. Experimental rate constants for water vapor absorption and desorption by Bu[6] have been determined to be 0.166 min−1 and 0.0221 min−1, respectively. The obtained results are in agreement with theoretical calculations using the DFT method. A hypothetical structure of bambus[6]uril tetrahydrate (Bu[6]·4H2O) has been proposed based on the experimental and DFT data.

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Izadifar, Mohammadreza, Neven Ukrainczyk und Eduardus Koenders. „Silicate Dissolution Mechanism from Metakaolinite Using Density Functional Theory“. Nanomaterials 13, Nr. 7 (27.03.2023): 1196. http://dx.doi.org/10.3390/nano13071196.

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Metakaolin (MK) is a high-quality, reactive nanomaterial that holds promising potential for large-scale use in improving the sustainability of cement and concrete production. It can replace cement due to its pozzolanic reaction with calcium hydroxide and water to form cementitious compounds. Therefore, understanding the dissolution mechanism is crucial to fully comprehending its pozzolanic reactivity. In this study, we present an approach for computing the activation energies required for the dissolution of metakaolin (MK) silicate units at far-from-equilibrium conditions using the improved dimer method (IDM) and the transition-state theory (TST) within density functional theory (DFT). Four different models were prepared to calculate the activation energies required for breaking oxo-bridging bonds between silicate or aluminate units. Our results showed that the activation energy for breaking the oxo-bridging bond to a silicate neighbor is higher than that to an aluminate neighbor due to the ionic interaction. However, for complete silicate tetrahedra dissolution, a higher activation energy is required for breaking the oxo-bridging bond to the aluminate neighbor compared to the silicate neighbor. The findings provide methodology for missing input data to predict the mesoscopic dissolution rate, e.g., by the atomistic kinetic Monte Carlo (KMC) upscaling approach.

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40

Vaivars, Guntars, Kristīne Krūkle-Bērziņa und Madara Markus. „Modelling IR Spectra of Sulfonated Polyether Ether Ketone (SPEEK) Membranes for Fuel Cells“. Key Engineering Materials 850 (Juni 2020): 138–43. http://dx.doi.org/10.4028/www.scientific.net/kem.850.138.

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SPEEK (sulfonated polyether ether ketone) membranes have been prepared and characterized. The SPEEK membrane geometry and theoretical vibration spectra calculated using density functional theory (DFT) as depending from membrane chain length and polymer cross-linking. Analyzed the limitations of the method by comparing theoretical and experimental IR spectra.

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41

White, Alexander J., Lee A. Collins, Katarina Nichols und S. X. Hu. „Mixed stochastic-deterministic time-dependent density functional theory: application to stopping power of warm dense carbon“. Journal of Physics: Condensed Matter 34, Nr. 17 (28.02.2022): 174001. http://dx.doi.org/10.1088/1361-648x/ac4f1a.

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Abstract Warm dense matter (WDM) describes an intermediate phase, between condensed matter and classical plasmas, found in natural and man-made systems. In a laboratory setting, WDM is often created dynamically. It is typically laser or pulse-power generated and can be difficult to characterize experimentally. Measuring the energy loss of high energy ions, caused by a WDM target, is both a promising diagnostic and of fundamental importance to inertial confinement fusion research. However, electron coupling, degeneracy, and quantum effects limit the accuracy of easily calculable kinetic models for stopping power, while high temperatures make the traditional tools of condensed matter, e.g. time-dependent density functional theory (TD-DFT), often intractable. We have developed a mixed stochastic-deterministic approach to TD-DFT which provides more efficient computation while maintaining the required precision for model discrimination. Recently, this approach showed significant improvement compared to models when compared to experimental energy loss measurements in WDM carbon. Here, we describe this approach and demonstrate its application to warm dense carbon stopping across a range of projectile velocities. We compare direct stopping-power calculation to approaches based on combining homogeneous electron gas response with bound electrons, with parameters extracted from our TD-DFT calculations.

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42

Borge-Durán, Ignacio, Denial Aias und Ilya Grinberg. „Modelling of high-temperature order–disorder phase transitions of non-stoichiometric Mo₂C and Ti₂C from first principles“. Physical Chemistry Chemical Physics 23, Nr. 39 (2021): 22305–12. http://dx.doi.org/10.1039/d1cp02935e.

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We constructed a simple atomistic potential capable of accurately reproducing the energetics of the carbon vacancy arrangements in cubic Mo2C and Ti2C obtained from density functional theory (DFT) calculations.

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43

Kuganathan, Navaratnarajah. „DFT Modelling of Tripeptides (Lysine-Tryptophan-Lysine) Interacting with Single Walled Carbon Nanotubes“. E-Journal of Chemistry 7, Nr. 3 (2010): 870–74. http://dx.doi.org/10.1155/2010/547219.

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Model calculations are performed to predict the nature of interaction between SWNT and a tripeptide (Lys-Trp-Lys) and to calculate the binding energies and charge transfer between these two species using density functional theory. DFT calculations indicate that the interaction is of a non covalent nature. Minimal charge transfer is observed between SWNT and Lys-Trp-Lys.

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Tošović, Jelena, und Urban Bren. „Antioxidative Action of Ellagic Acid—A Kinetic DFT Study“. Antioxidants 9, Nr. 7 (06.07.2020): 587. http://dx.doi.org/10.3390/antiox9070587.

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Although one can find numerous studies devoted to the investigation of antioxidative activity of ellagic acid (EA) in the scientific literature, the mechanisms of its action have not yet been fully clarified. Therefore, further kinetic studies are needed to understand its antioxidative capacity completely. This work aims to reveal the underlying molecular mechanisms responsible for the antioxidative action of EA. For this purpose, its reactions with HO• and CCl3OO• radicals were simulated at physiological conditions using the quantum mechanics-based test for overall free-radical scavenging activity. The density functional theory in combination with the conductor-like polarizable continuum solvation model was utilized. With HO• radical EA conforms to the hydrogen atom transfer and radical adduct formation mechanisms, whereas sequential proton loss electron transfer mechanism is responsible for scavenging of CCl3OO• radical. In addition, compared to trolox, EA was found more reactive toward HO•, but less reactive toward CCl3OO•. The calculated rate constants for the reactions of EA with both free radicals are in a very good agreement with the corresponding experimental values.

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45

Hou, Li-Jie, Bo-Wan Wu, Yan-Xia Han, Chao Kong, Dong-Ping Chen und Li-Guo Gao. „Density functional theoretical study on the reaction mechanism of SiHF radical with HNCO“. Journal of Theoretical and Computational Chemistry 13, Nr. 07 (November 2014): 1450054. http://dx.doi.org/10.1142/s0219633614500540.

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The reaction mechanism of SiHF radical with HNCO has been investigated by the B3LYP method of density functional theory (DFT), while the geometries and harmonic vibration frequencies of reactants, intermediates, transition states and products have been calculated at the B3LYP/6-311++G** level. To obtain more precise energy result, stationary point energies were calculated at the CCSD(T)/6-311++G**//B3LYP/6-311++G** level. In temperature range of 100 K to 1900 K, the statistical thermodynamics and Eyring transition state theory with Winger correction are used to study the thermodynamic and kinetic characters of the channel with low energy barrier at 1.0 Atm. SiHF + HNCO → IM 8 → TS 8 → SiFNHCHO ( P 3) was the main channel with low potential energy in the singlet state, SiFNHCHO was the main product. The analyses for the combining interaction between SiHF radical and HNCO with the atom-in-molecules (AIM) theory have been performed. There are three reaction channels in the triplet.

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Sun, Min, Zi Li, Guo-Zhen Zhu, Wen-Qing Liu, Shao-Hua Liu und Chong-Yu Wang. „Diffusion in Ni-Based Single Crystal Superalloys with Density Functional Theory and Kinetic Monte Carlo Method“. Communications in Computational Physics 20, Nr. 3 (31.08.2016): 603–18. http://dx.doi.org/10.4208/cicp.111115.271115a.

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AbstractIn the paper, we focus on atom diffusion behavior in Ni-based superalloys, which have important applications in the aero-industry. Specifically, the expressions of the key physical parameter – transition rate (jump rate) in the diffusion can be given from the diffusion theory in solids and the kinetic Monte Carlo (KMC) method, respectively. The transition rate controls the diffusion process and is directly related to the energy of vacancy formation and the energy of migration of atom from density functional theory (DFT). Moreover, from the KMC calculations, the diffusion coefficients for Ni and Al atoms in the γ phase (Ni matrix) and the γʹ phase (intermetallic compound Ni3Al) of the superalloy have been obtained. We propose a strategy of time stepping to deal with the multi-time scale issues. In addition, the influence of temperature and Al concentration on diffusion in dilute alloys is also reported.

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47

Li, Junfu, James O’Shea, Xianghui Hou und George Z. Chen. „Faradaic processes beyond Nernst's law: density functional theory assisted modelling of partial electron delocalisation and pseudocapacitance in graphene oxides“. Chemical Communications 53, Nr. 75 (2017): 10414–17. http://dx.doi.org/10.1039/c7cc04344a.

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DFT studies of graphene oxide models suggest that the transfer of partially delocalised electrons does not follow Nernst's Law, but explain well the common experimental observations of pseudocapacitance.

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48

Pintus, Anna, M. Carla Aragoni, Gianfranco Carcangiu, Laura Giacopetti, Francesco Isaia, Vito Lippolis, Laura Maiore, Paola Meloni und Massimiliano Arca. „Density functional theory modelling of protective agents for carbonate stones: a case study of oxalate and oxamate inorganic salts“. New Journal of Chemistry 42, Nr. 14 (2018): 11593–600. http://dx.doi.org/10.1039/c8nj01714j.

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DFT calculations allowed investigating the ability of oxalate monoesters and monoamides salts to act as protective agents for carbonate stones, such as marble or limestones, of historical interest in the field of cultural heritage.

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Giry, Clément, David Bertrand, Alexandre Pierret, Emeline Vedrenne, Corinne Lacaze-Dufaure, Jean-François Fabre, Sophie Thiebaud-Roux, Carlos Vaca Garcia und Christine Cecutti. „Synthesis and Characterization of a New Organocatalytic Biosourced Surfactant“. Sustainable Chemistry 2, Nr. 2 (07.05.2021): 335–42. http://dx.doi.org/10.3390/suschem2020019.

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This article describes the synthesis of a new bio-based organocatalytic surfactant. The nine steps of the synthesis were optimized, fully respecting the principles of green chemistry. The surfactant aspect was then evaluated with the use of tensiometric studies. The molecular organization of the surfactant in vesicles in an aqueous medium was characterized by Dynamic Light Scattering (DLS) and confirmed using Density Functional Theory (DFT) modelling.

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50

Ying, Yiran, Ke Fan, Xin Luo, Jinli Qiao und Haitao Huang. „Unravelling the origin of bifunctional OER/ORR activity for single-atom catalysts supported on C2N by DFT and machine learning“. Journal of Materials Chemistry A 9, Nr. 31 (2021): 16860–67. http://dx.doi.org/10.1039/d1ta04256d.

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A group of bifunctional oxygen evolution/reduction reaction single-atom catalysts supported on C₂N, is proposed. The origin of their high catalytic activity is elucidated by density functional theory calculations and machine learning modelling.

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