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Keywords = ab initio molecular dynamics simulation (AIMD)

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19 pages, 2474 KiB  
Article
Unraveling the Role of Aluminum in Boosting Lithium-Ionic Conductivity of LLZO
by Md Mozammal Raju, Yi Ding and Qifeng Zhang
Electrochem 2025, 6(3), 29; https://doi.org/10.3390/electrochem6030029 - 4 Aug 2025
Abstract
The development of high-performance solid electrolytes is critical to advancing solid-state lithium-ion batteries (SSBs), with lithium lanthanum zirconium oxide (LLZO) emerging as a leading candidate due to its chemical stability and wide electrochemical window. In this study, we systematically investigated the effects of [...] Read more.
The development of high-performance solid electrolytes is critical to advancing solid-state lithium-ion batteries (SSBs), with lithium lanthanum zirconium oxide (LLZO) emerging as a leading candidate due to its chemical stability and wide electrochemical window. In this study, we systematically investigated the effects of cation dopants, including aluminum (Al3+), tantalum (Ta5+), gallium (Ga3+), and rubidium (Rb+), on the structural, electronic, and ionic transport properties of LLZO using density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations. It appeared that, among all simulated results, Al-LLZO exhibits the highest ionic conductivity of 1.439 × 10−2 S/cm with reduced activation energy of 0.138 eV, driven by enhanced lithium vacancy concentrations and preserved cubic-phase stability. Ta-LLZO follows, with a conductivity of 7.12 × 10−3 S/cm, while Ga-LLZO and Rb-LLZO provide moderate conductivity of 3.73 × 10−3 S/cm and 3.32 × 10−3 S/cm, respectively. Charge density analysis reveals that Al and Ta dopants facilitate smoother lithium-ion migration by minimizing electrostatic barriers. Furthermore, Al-LLZO demonstrates low electronic conductivity (1.72 × 10−8 S/cm) and favorable binding energy, mitigating dendrite formation risks. Comparative evaluations of radial distribution functions (RDFs) and XRD patterns confirm the structural integrity of doped systems. Overall, Al emerges as the most effective and economically viable dopant, optimizing LLZO for scalable, durable, and high-conductivity solid-state batteries. Full article
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27 pages, 5575 KiB  
Review
Modeling of Chemiresistive Gas Sensors: From Microscopic Reception and Transduction Processes to Macroscopic Sensing Behaviors
by Zhiqiao Gao, Menglei Mao, Jiuwu Ma, Jincheng Han, Hengzhen Feng, Wenzhong Lou, Yixin Wang and Teng Ma
Chemosensors 2025, 13(7), 227; https://doi.org/10.3390/chemosensors13070227 - 22 Jun 2025
Viewed by 661
Abstract
Chemiresistive gas sensors have gained significant attention and have been widely applied in various fields. However, the gap between experimental observations and fundamental sensing mechanisms hinders systematic optimization. Despite the critical role of modeling in explaining atomic-scale interactions and offering predictive insights beyond [...] Read more.
Chemiresistive gas sensors have gained significant attention and have been widely applied in various fields. However, the gap between experimental observations and fundamental sensing mechanisms hinders systematic optimization. Despite the critical role of modeling in explaining atomic-scale interactions and offering predictive insights beyond experiments, existing reviews on chemiresistive gas sensors remain predominantly experimental-centric, with a limited systematic exploration of the modeling approaches. Herein, we present a comprehensive overview of the modeling approaches for chemiresistive gas sensors, focusing on two critical processes: the reception and transduction stages. For the reception process, density functional theory (DFT), molecular dynamics (MD), ab initio molecular dynamics (AIMD), and Monte Carlo (MC) methods were analyzed. DFT quantifies atomic-scale charge transfer, and orbital hybridization, MD/AIMD captures dynamic adsorption kinetics, and MC simulates equilibrium/non-equilibrium behaviors based on statistical mechanics principles. For the transduction process, band-bending-based theoretical models and power-law models elucidate the resistance modulation mechanisms, although their generalizability remains limited. Notably, the finite element method (FEM) has emerged as a powerful tool for full-process modeling by integrating gas diffusion, adsorption, and electronic responses into a unified framework. Future directions highlight the use of multiscale models to bridge microscopic interactions with macroscopic behaviors and the integration of machine learning, accelerating the iterative design of next-generation sensors with superior performance. Full article
(This article belongs to the Special Issue Functional Nanomaterial-Based Gas Sensors and Humidity Sensors)
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16 pages, 2229 KiB  
Article
Investigation of the Effect of Molecules Containing Sulfonamide Moiety Adsorbed on the FAPbI3 Perovskite Surface: A First-Principles Study
by Shiyan Yang, Yu Zhuang, Youbo Dou, Jianjun Wang, Hongwen Zhang, Wenjing Lu, Qiuli Zhang, Xihua Zhang, Yuan Wu and Xianfeng Jiang
Molecules 2025, 30(11), 2463; https://doi.org/10.3390/molecules30112463 - 4 Jun 2025
Viewed by 522
Abstract
First-principles calculations were conducted to examine the impact of three sulfonamide-containing molecules (H4N2O2S, CH8N4O3S, and C2H2N6O4S) adsorbed on the FAPbI3(001) perovskite [...] Read more.
First-principles calculations were conducted to examine the impact of three sulfonamide-containing molecules (H4N2O2S, CH8N4O3S, and C2H2N6O4S) adsorbed on the FAPbI3(001) perovskite surface, aiming to establish a significant positive correlation between the molecular structures and their regulatory effects on the perovskite surface. A systematic comparison was conducted to evaluate the adsorption stability of the three molecules on the two distinct surface terminations. The results show that all three molecules exhibit strong adsorption on the FAPbI3(001) surface, with C2H12N6O4S demonstrating the most favorable binding stability due to its extended frameworks and multiple electron-donating/withdrawing groups. Simpler molecules lacking carbon skeletons exhibit weaker adsorption and less dependence on surface termination. Ab initio molecular dynamics simulations (AIMD) further corroborated the thermal stability of the stable adsorption configurations at elevated temperatures. Electronic structure analysis reveals that molecular adsorption significantly reconstructs the density of states (DOS) on the PbI2-terminated surface, inducing shifts in band-edge states and enhancing energy-level coupling between molecular orbitals and surface states. In contrast, the FAI-terminated surface shows weaker interactions. Charge density difference (CDD) analysis indicates that the molecules form multiple coordination bonds (e.g., Pb–O, Pb–S, and Pb–N) with uncoordinated Pb atoms, facilitated by –SO2–NH2 groups. Bader charge and work function analyses indicate that the PbI2-terminated surface exhibits more pronounced electronic coupling and interfacial charge transfer. The C2H12N6O4S adsorption system demonstrates the most substantial reduction in work function. Optical property calculations show a distinct red-shift in the absorption edge along both the XX and YY directions for all adsorption systems, accompanied by enhanced absorption intensity and broadened spectral range. These findings suggest that sulfonamide-containing molecules, particularly C2H12N6O4S with extended carbon skeletons, can effectively stabilize the perovskite interface, optimize charge transport pathways, and enhance light-harvesting performance. Full article
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29 pages, 7563 KiB  
Article
Influence of Fluorine Doping on Rutile TiO2 Nanostructures for Visible-Light-Driven Photocatalysis: A DFT + U Study
by Fikadu Takele Geldasa and Francis Birhanu Dejene
Nanomaterials 2025, 15(9), 694; https://doi.org/10.3390/nano15090694 - 5 May 2025
Cited by 2 | Viewed by 546
Abstract
In this work, a density functional theory (DFT) with Hubbard correction (U) approaches implemented through the Quantum ESPRESSO code is utilized to investigate the effects of fluorine (F) doping on the structural, electronic, and optical properties of rutile TiO2. Rutile TiO [...] Read more.
In this work, a density functional theory (DFT) with Hubbard correction (U) approaches implemented through the Quantum ESPRESSO code is utilized to investigate the effects of fluorine (F) doping on the structural, electronic, and optical properties of rutile TiO2. Rutile TiO2 is a promising material for renewable energy production and environmental remediation, but its wide bandgap limits its application to the UV spectrum, which is narrow and expensive. To extend the absorption edge of TiO2 into the visible light range, different concentrations of F were substituted at oxygen atom sites. The structural analysis reveals that the lattice constants and bond lengths of TiO2 increased with F concentrations. Ab initio molecular dynamics simulations (AIMD) at 1000 K confirm that both pristine and F-doped rutile TiO2 maintains structural integrity, indicating excellent thermal stability essential for high-temperature photocatalytic applications. Band structure calculations show that pure rutile TiO2 has a bandgap of 3.0 eV, which increases as the F concentration rises, with the 0.25 F-doped structures exhibiting an even larger bandgap, preventing it from responding to visible light. The absorption edge of doped TiO2 shifts towards the visible region, as shown by the imaginary part of the dielectric function. This research provides valuable insights for experimentalists, helping them understand how varying F concentrations influence the properties of rutile TiO2 for photocatalytic applications. Full article
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17 pages, 5566 KiB  
Article
Elemental Interactions and Local Structures in Liquid Sb-As and Sb-Al-As Alloys: Insights from Ab Initio Molecular Dynamics and Experimental Studies on As Aggregation and Diffusion Behaviors
by Zongbo Li, Yan Feng, Qiyue Wu, Yufeng Wen, Xiang Peng and Richu Wang
Materials 2025, 18(7), 1633; https://doi.org/10.3390/ma18071633 - 3 Apr 2025
Viewed by 317
Abstract
The local structure, element interactions, and electronic structure properties in Sb-As and Sb-Al-As melts were studied using ab initio molecular dynamics (AIMD) simulations. Sb-0.1wt%Al alloy was prepared using vacuum melting, and both pure Sb and Sb-0.1wt%Al alloys were subjected to zone refining experiments [...] Read more.
The local structure, element interactions, and electronic structure properties in Sb-As and Sb-Al-As melts were studied using ab initio molecular dynamics (AIMD) simulations. Sb-0.1wt%Al alloy was prepared using vacuum melting, and both pure Sb and Sb-0.1wt%Al alloys were subjected to zone refining experiments to investigate the effect of Al addition on the removal efficiency of impurity As. The results show that in the Sb-Al-As ternary melt, the interaction between Al and As atoms is stronger than the interactions between other solvent atoms. The introduction of Al disrupts the Sb-As and As-As bonds, promoting the formation of Al-As bonds, which alters the state of As atoms in the melt and subsequently affects their diffusion properties. The study elucidates the kinetic process of Al-As bond formation in the melt. The bond-angle distribution function and the coordination polyhedron sequence indicate that with the addition of Al atoms, the geometric configuration around As atoms in the Sb melt and the types and numbers of clusters undergo significant changes. A strong hybridization occurs between the 4p orbitals of As atoms and the 3p orbitals of Al atoms. Moreover, the noticeable charge accumulation between Al and As atoms suggests a strong interaction between them. The addition of aluminum increased the removal rate of arsenic impurities in antimony from 67.27% to 83.24%, significantly enhancing the efficiency of arsenic removal. Full article
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17 pages, 1042 KiB  
Article
Experimental and Theoretical Study of the Synthesis of a Deep Eutectic Solvent Based on Protonated Caffeine, Ethylene Glycol, and ZnCl2
by Laura Sofía Benavides-Maya, Manuel Felipe Torres-Perdomo, Luz M. Ocampo-Carmona and Luver Echeverry-Vargas
Molecules 2025, 30(7), 1557; https://doi.org/10.3390/molecules30071557 - 31 Mar 2025
Cited by 1 | Viewed by 923
Abstract
In this study, a deep eutectic solvent (DES) incorporating protonated caffeine (CafCl), ethylene glycol (EG), and zinc chloride (ZnCl2) was synthesized and characterized for the first time. Caffeine was protonated using an optimized procedure in an anhydrous medium to enhance [...] Read more.
In this study, a deep eutectic solvent (DES) incorporating protonated caffeine (CafCl), ethylene glycol (EG), and zinc chloride (ZnCl2) was synthesized and characterized for the first time. Caffeine was protonated using an optimized procedure in an anhydrous medium to enhance its interaction with the system, and its structure was confirmed by FTIR spectroscopy, NMR, and thermogravimetric analysis (TGA), evidencing the formation of the N-H bond in the imidazole ring. A eutectic mixture with a molar ratio of ETG:ZnCl2:CafCl of 1:2:0.1 was synthesized, and its characterization confirmed the formation of hydrogen bonds and the coordinative interaction between the components. Additionally, computational simulations based on COSMO-RS and ab initio molecular dynamics (AIMD) were conducted to analyze the charge distribution and the stability of the hydrogen bond network in the eutectic mixture. Sigma profiles revealed that protonated caffeine possesses highly polar regions capable of establishing strong interactions with EG and ZnCl2, enhancing the system’s stability. Furthermore, radial distribution functions (RDFs) showed a decrease in the interaction distance between key atoms after incorporating protonated caffeine. The results suggest that this novel DES has promising potential for industrial applications, especially in the extraction of sulfur compounds from fossil fuels due to the activation of the imidazole ring of caffeine. However, further studies are needed to optimize its operating conditions and evaluate its performance on an industrial scale. Full article
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17 pages, 3718 KiB  
Article
Modeling the Carbothermal Chlorination Mechanism of Titanium Dioxide in Molten Salt Using a Deep Neural Network Potential
by Enhao Zhang, Xiumin Chen, Jie Zhou, Huapeng Wu, Yunmin Chen, Haiguang Huang, Jianjun Li and Qian Yang
Materials 2025, 18(3), 659; https://doi.org/10.3390/ma18030659 - 2 Feb 2025
Viewed by 1062
Abstract
The molten salt chlorination method is one of the two main methods for producing titanium tetrachloride, an important intermediate product in the titanium industry. To effectively improve chlorination efficiency and reduce unnecessary waste salt generation, it is necessary to understand the mechanism of [...] Read more.
The molten salt chlorination method is one of the two main methods for producing titanium tetrachloride, an important intermediate product in the titanium industry. To effectively improve chlorination efficiency and reduce unnecessary waste salt generation, it is necessary to understand the mechanism of the molten salt chlorination reaction, and consequently this paper conducted studies on the carbon chlorination reaction mechanism in molten salts by combining ab initio molecular dynamics (AIMD) and deep potential molecular dynamics (DeePMD) methods. The use of DeePMD allowed for simulations on a larger spatial and longer time scale, overcoming the limitations of AIMD in fully observing complex reaction processes. The results comprehensively revealed the mechanism of titanium dioxide transforming into titanium tetrachloride. In addition, the presence form and conversion pathways of chlorine in the system were elucidated, and it was observed that chloride ions derived from NaCl can chlorinate titanium dioxide to yield titanium tetrachloride, which was validated through experimental studies. Self-diffusion coefficients of chloride ions in pure NaCl which were acquired by DeePMD showed good agreement with the experimental data. Full article
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14 pages, 4697 KiB  
Article
Effect of Inherent Mg/Ti Interface Structure on Element Segregation and Bonding Behavior: An Ab Initio Study
by Xiaodong Zhu, Kaiming Cheng, Jin Wang, Jianbo Li, Jingya Wang, Huan Yu, Jixue Zhou and Yong Du
Materials 2025, 18(2), 409; https://doi.org/10.3390/ma18020409 - 16 Jan 2025
Viewed by 815
Abstract
To provide insight into the interface structure in Ti particle-reinforced Mg matrix composites, this study investigates the inherent Mg/Ti interface structure formed during the solidification of supercooled Mg melt on a (0001)Ti substrate using ab initio molecular dynamics (AIMD) simulations and density function [...] Read more.
To provide insight into the interface structure in Ti particle-reinforced Mg matrix composites, this study investigates the inherent Mg/Ti interface structure formed during the solidification of supercooled Mg melt on a (0001)Ti substrate using ab initio molecular dynamics (AIMD) simulations and density function theory (DFT) calculation. The resulting interface exhibits an orientation relationship of 0001Mg//0001Ti with a lattice mismatch of approximately 8%. Detailed characterizations reveal the occurrences of 0001Mg plane rotation and vacancy formation to overcome the lattice mismatch at the inherent Mg/Ti interface while allowing Mg atoms to occupy the energetically favorable hollow sites above the Ti atomic layer. The atomic diffusion behaviors of rare-earth elements Gd and Y at the Mg/Ti interface was examined using the climbing image nudged elastic band (CI-NEB) method, demonstrating a strong segregation tendency towards the interface promoted by the inherent interface structure. Additionally, the calculated Griffith work indicates enhanced interfacial adhesion due to the segregation of Gd and Y, which is beneficial for the mechanical properties of the composite. Full article
(This article belongs to the Special Issue Light Alloys and High-Temperature Alloys (Volume II))
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13 pages, 4985 KiB  
Article
Unveiling the Photocatalytic Potential of BiAgOS Solid Solution for Hydrogen Evolution Reaction
by Oumaima Ben Abdelhadi, Majid El Kassaoui, Hajar Moatassim, Ahmed Kotbi, Mohamed Balli, Omar Mounkachi and Mustapha Jouiad
Nanomaterials 2024, 14(23), 1869; https://doi.org/10.3390/nano14231869 - 22 Nov 2024
Cited by 2 | Viewed by 1496
Abstract
The growing emphasis on green energy has spurred momentum in research and development within the field of photocatalytic materials, particularly for green hydrogen production. Among the most abundant oxides on Earth, oxychalcogenides stand out for their cost-effectiveness and ease of synthesis. In this [...] Read more.
The growing emphasis on green energy has spurred momentum in research and development within the field of photocatalytic materials, particularly for green hydrogen production. Among the most abundant oxides on Earth, oxychalcogenides stand out for their cost-effectiveness and ease of synthesis. In this context, we present an investigation of the potential use of BiAgOS as an efficient photocatalyst for hydrogen generation. Utilizing density functional theory and ab initio molecular dynamics (AIMD) simulations, we computed its physical properties and assessed its photocatalytic performance. Specifically, using Heyd–Scuseria–Ernzerhof corrections, our calculations yielded an appropriate electronic gap of ~1.47 eV necessary for driving the water-splitting reaction. Additionally, we obtained a very high optical absorption coefficient of ~5 × 105/cm–1 and an estimation of hydrogen generation yield of ~289.56 µmol∙g–1. These findings suggest that BiAgOS holds promise for enabling the development of cheap, reliable, and highly efficient photocatalysts for hydrogen production. Full article
(This article belongs to the Special Issue Advanced Nanomaterials for Photocatalysis)
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13 pages, 2718 KiB  
Article
Crystal Chemistry at Interfaces Between Liquid Al and Polar SiC{0001} Substrates
by Changming Fang and Zhongyun Fan
Metals 2024, 14(11), 1258; https://doi.org/10.3390/met14111258 - 6 Nov 2024
Viewed by 956
Abstract
Silicon carbide (SiC) has been widely added into light metals, e.g., Al, to enhance their mechanical performance and corrosion resistance. SiC particle-reinforced metal matrix composites (SiC-MMCs) exhibit low weight/volume ratios, high strength/hardness, high corrosion resistance, and thermal stability. They have potential applications in [...] Read more.
Silicon carbide (SiC) has been widely added into light metals, e.g., Al, to enhance their mechanical performance and corrosion resistance. SiC particle-reinforced metal matrix composites (SiC-MMCs) exhibit low weight/volume ratios, high strength/hardness, high corrosion resistance, and thermal stability. They have potential applications in aerospace, automobiles, and other specialized equipment. The macro-mechanical properties of Al/SiC composites depend on the local structures and chemical interactions at the Al/SiC interfaces at the atomic level. Moreover, the added SiC particles may act as potential nucleation sites during solidification. We investigate local atomic ordering and chemical interactions at the interfaces between liquid Al (Al(l) in short) and polar SiC substrates using ab initio molecular dynamics (AIMD) methods. The simulations reveal a rich variety of interfacial interactions. Charge transfer occurs from Al(l) to C-terminating atoms (Δq = 0.3e/Al on average), while chemical bonding between interfacial Si and Al(l) atoms is more covalent with a minor charge transfer of Δq = 0.04e/Al. The prenucleation at both interfaces is moderate with three to four recognizable layers. The information obtained here helps increase understanding of the interfacial interactions at Al/SiC at the atomic level and the related macro-mechanical properties, which is helpful in designing novel SiC-MMC materials with desirable properties and optimizing related manufacturing and machining processes. Full article
(This article belongs to the Special Issue Multi-scale Simulation of Metallic Materials (2nd Edition))
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10 pages, 1009 KiB  
Article
First Principles Study of the Phase Stability, the Li Ionic Diffusion, and the Conductivity of the Li10GexMo1−xP2S12 of Superionic Conductors
by Yifang Wu, Yuanzhen Chen and Shaokun Chong
Batteries 2024, 10(10), 344; https://doi.org/10.3390/batteries10100344 - 27 Sep 2024
Cited by 1 | Viewed by 1471
Abstract
Using first-principles density functional theory (DFT) calculations and ab initio molecular dynamics (AIMD) simulations, we performed this study on the phase stability, the intrinsic redox stability, and the Li+ conductivity of Li10GexMo1−xP2S12 (x [...] Read more.
Using first-principles density functional theory (DFT) calculations and ab initio molecular dynamics (AIMD) simulations, we performed this study on the phase stability, the intrinsic redox stability, and the Li+ conductivity of Li10GexMo1−xP2S12 (x = 0~1) superionic conductors. Molybdenum (Mo) is expected to replace expensive germanium (Ge) to lower tmaterial costs, reduce sensitivity to ambient water and oxygen, and achieve acceptable Li+ conductivity. The ab initio first principle molecular dynamics simulations show that room-temperature Li+ conductivity is 1.12 mS·cm−1 for the Li10Ge0.75Mo0.25P2S12 compound, which is comparable to the theoretical value of 6.81 mS·cm−1 and the experimental measured one of 12 mS·cm−1 of the Li10GeP2S12 (LGPS) structure. For Li10GexMo1−xP2S12 (x = 0, 0.25, 0.5 and 1) compounds, the density of states and the projection fractional wave state density were calculated. It was found that when Ge atoms were partially replaced by Mo atoms, the band gap remained unchanged at 2.5 eV, but deep level defects appeared in Mo-substituted compounds. Fortunately, this deep level defect is difficult to ionize at room temperature, so it has no effect on the electronic conductivity of Mo substitute compounds, making Mo substitution a suitable solution for electrolyte materials. The projection fractional wave state density calculation shows that the covalent bond between Mo and S is stronger than that between Ge and S, which reduces the sensitivity of Mo-substituted compounds to water and oxygen contents in the air. In addition, the partial state density coincidence curve between Li and S elements disappears in the 25% Mo-substituted compound with energies of 4–5 eV, indicating that the Li2S by-product is decreased. Full article
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20 pages, 7721 KiB  
Article
Role of Multiple Intermolecular H-Bonding Interactions in Molecular Cluster of Hydroxyl-Functionalized Imidazolium Ionic Liquid: An Experimental, Topological, and Molecular Dynamics Study
by Sumit Kumar Panja, Sumit Kumar, Boumediene Haddad, Abhishek R. Patel, Didier Villemin, Hakkoum-Mohamed Amine, Sayantan Bera and Mansour Debdab
Physchem 2024, 4(4), 369-388; https://doi.org/10.3390/physchem4040026 - 24 Sep 2024
Cited by 3 | Viewed by 2338
Abstract
Multiple intermolecular H-bonding interactions play a pivotal role in determining the macroscopic state of ionic liquids (ILs). Hence, the relationship between the microscopic and the macroscopic properties is key for a rational design of new imidazolium ILs. In the present work, we investigated [...] Read more.
Multiple intermolecular H-bonding interactions play a pivotal role in determining the macroscopic state of ionic liquids (ILs). Hence, the relationship between the microscopic and the macroscopic properties is key for a rational design of new imidazolium ILs. In the present work, we investigated how the physicochemical property of hydroxyl-functionalized imidazolium chloride is connected to the molecular structure and intermolecular interactions. In the isolated ion pair, strong N-H···Cl H-bonding interactions are observed rather than H-bonding interactions at the acidic C2-H site and alkyl-OH···Cl of the hydroxyl-functionalized imidazolium chloride. However, the N-H···Cl H-bonding interaction of the cation plays a significant role in ion-pair formations and polymeric clusters. For 3-(2-Hydroxy)-1H-imidazolium chloride (EtOHImCl), the oxygen atom (O) engages in two significant interactions within its homodimeric ion-pair cluster: N-H···O and alkyl OH···Cl. Vibrational spectroscopy and DFT calculations reveal that the chloride ion (Cl) forms a hydrogen bond with the C2-H group via a C2-H···Cl interaction site. Natural Bond Orbital (NBO) analysis indicates that the O-H···Cl hydrogen-bonding interaction is crucial for the stability of the IL, with a second-order perturbation energy of approximately 133.8 kJ/mol. Additional computational studies using Atoms in Molecules (AIMs), non-covalent interaction (NCI) analysis, Electron Localization Function (ELF), and Localized Orbital Locator (LOL) provide significant insights into the properties and nature of non-covalent interactions in ILs. Ab initio molecular dynamics (AIMD) simulations of the IL demonstrate its stable states with relatively low energy values around −1680.6510 atomic units (a.u.) at both 100 fs and 400 fs due to O-H···Cl and C-H···Cl interactions. Full article
(This article belongs to the Section Experimental and Computational Spectroscopy)
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17 pages, 2354 KiB  
Article
A Molecular Dynamics Simulation Study of Crystalline and Liquid MgO
by Anatoly S. Arkhipin, Alexander Pisch, Irina A. Uspenskaya and Noël Jakse
Ceramics 2024, 7(3), 1187-1203; https://doi.org/10.3390/ceramics7030078 - 4 Sep 2024
Cited by 3 | Viewed by 1568
Abstract
Classical (MD) and ab initio (AIMD) molecular dynamics simulations were conducted to investigate the fundamental properties of solid and liquid MgO. AIMD was performed by DFT using the Strongly Conditioned and Appropriately Normed (SCAN) exchange correlation functional. The obtained pair-correlation functions of liquid [...] Read more.
Classical (MD) and ab initio (AIMD) molecular dynamics simulations were conducted to investigate the fundamental properties of solid and liquid MgO. AIMD was performed by DFT using the Strongly Conditioned and Appropriately Normed (SCAN) exchange correlation functional. The obtained pair-correlation functions of liquid MgO were used as reference data for the optimization of parameters of classical MD. For the latter, a Born–Mayer–Huggins (BMH) potential was applied, and parameters were adjusted until a best fit of both structural properties was obtained by AIMD and physical properties by experimental data. Different structural, dynamic and thermodynamic properties of solid and liquid MgO were then calculated by classical MD and compared with the literature data. Good agreement was found for the Mg-O bond length, self-diffusion coefficients, density of liquid MgO and for heat content and density of crystalline MgO. Using a void-melting approach, the melting temperature of MgO was found as 3295 ± 30 K, which is in good agreement with the recent experimental work by Ronchi et al. (3250 ± 20 K). The optimized parameters of BMH potential describe well the structural, dynamic and thermodynamic properties of solid and liquid MgO and may be combined with our previous results of a CaO-Al2O3-TiO2 system to calculate the properties of a quaternary CaO-MgO-Al2O3-TiO2 system. Full article
(This article belongs to the Special Issue Advances in Ceramics, 2nd Edition)
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9 pages, 2905 KiB  
Article
Ab Initio Investigation of Oxygen Ion Diffusion in the Layered Perovskite System YSr2Cu2FeO7+δ (0 < δ < 1)
by Marianela Gómez-Toledo and Elena M. Arroyo-de Dompablo
Appl. Sci. 2024, 14(15), 6586; https://doi.org/10.3390/app14156586 - 27 Jul 2024
Cited by 3 | Viewed by 1463
Abstract
Extensive research on transition metal perovskite oxides as electrodes in solid oxide cells (SOC) has highlighted the potential ability of Fe-based perovskite oxides to catalyze oxygen reduction/evolution reactions (ORR/OER). The layered perovskite-type system YSr2Cu2FeO7+δ has been reported to [...] Read more.
Extensive research on transition metal perovskite oxides as electrodes in solid oxide cells (SOC) has highlighted the potential ability of Fe-based perovskite oxides to catalyze oxygen reduction/evolution reactions (ORR/OER). The layered perovskite-type system YSr2Cu2FeO7+δ has been reported to possess attractive electrocatalytic properties. This work applies density functional theory (DFT) calculations to investigate oxygen ion diffusion in the YSr2Cu2FeO7+δ system. For δ = 0.5, it is found that in the most stable configuration, the oxygen vacancies in the FeO1+δ plane are arranged to form Fe ions in tetrahedral, square pyramid, and octahedral coordination. Ab initio molecular dynamics (AIMD) simulations for YSr2Cu2FeO7.5 (δ = 0.5) yield an oxygen ion diffusion coefficient of 1.28 × 10−7 cm2/s at 500 °C (Ea = 0.37 eV). Complementary results for YSr2Cu2FeO7.2 (δ = 0.2) and YSr2Cu2FeO7.75 (δ = 0.75) indicate that the oxygen diffusion occurs in the FeO1+δ plane, and depends on the oxygen vacancies distribution around the Fe centers. Full article
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16 pages, 11736 KiB  
Article
Exploring the Structural and Electronic Properties of Niobium Carbide Clusters: A Density Functional Theory Study
by Hui-Fang Li, Huai-Qian Wang and Yu-Kun Zhang
Molecules 2024, 29(13), 3238; https://doi.org/10.3390/molecules29133238 - 8 Jul 2024
Cited by 1 | Viewed by 1614
Abstract
This paper systematically investigates the structure, stability, and electronic properties of niobium carbide clusters, NbmCn (m = 5, 6; n = 1–7), using density functional theory. Nb5C2 and Nb5C6 possess higher dissociation energies and [...] Read more.
This paper systematically investigates the structure, stability, and electronic properties of niobium carbide clusters, NbmCn (m = 5, 6; n = 1–7), using density functional theory. Nb5C2 and Nb5C6 possess higher dissociation energies and second-order difference energies, indicating that they have higher thermodynamic stability. Moreover, ab initio molecular dynamics (AIMD) simulations are used to demonstrate the thermal stability of these structures. The analysis of the density of states indicates that the molecular orbitals of NbmCn (m = 5, 6; n = 1–7) are primarily contributed by niobium atoms, with carbon atoms having a smaller contribution. The composition of the frontier molecular orbitals reveals that niobium atoms contribute approximately 73.1% to 99.8% to NbmCn clusters, while carbon atoms contribute about 0.2% to 26.9%. Full article
(This article belongs to the Topic Advances in Computational Materials Sciences)
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