Accurate determination of the potential of zero free charge (PZFC) of an electrode from abinitio molecular dynamics (AIMD) simulations remains a longstanding challenge, largely due to ambiguities in computational setups and potential referencing at electrochemical interfaces. Here, we critically assess two widely used referencing strategies, the work-function (WF) and computational standard hydrogen electrode (cSHE) approaches, by combining a comprehensive analysis of literature data with new AIMD results. We demonstrate that both methods suffer from intrinsic limitations, arising from statistical uncertainty at the water/vacuum interface (WF) and from a strong dependence on setup-specific inner reference energies (cSHE). To overcome these shortcomings, we introduce a revised work-function approach (revWF) that unifies the strengths of both schemes while avoiding their principal weaknesses. The revWF method enables a more transferable and computationally efficient determination of the PZFC. Beyond these methodological considerations, we also reexamine and summarize the physical interpretation of the PZFC within the framework of an analysis originally suggested by Trasatti. Overall, this work provides practical guidelines for evaluating computational PZFCs and establishes revWF as a robust reference scheme for AIMD simulations of electrochemical interfaces.

Electrolyte additives such as fluoroethylene carbonate (FEC) and vinylene carbonate (VC) improve lithium-ion battery performance, yet whether they shift product distributions along common pathways or select fundamentally different decomposition channels remains debated. Here, ensemble ab initio molecular dynamics simulations coupled with machine learning structural analysis quantify how electrolyte composition controls access to configuration space during early solid-electrolyte interphase (SEI) formation. Analysis of 15 independent trajectories across baseline, FEC-rich, and VC-rich formulations using SOAP descriptors, UMAP, and HDBSCAN reveals that each composition occupies nonoverlapping structural regions characterized by distinct Li-O coordination environments and composition-dependent Li-F signatures. Diagnostic comparison of initial and evolved configurations, including Li-centered SOAP descriptors that isolate emergent structural changes from compositional encoding, and supported by time-resolved SOAP analysis, provides evidence that this separation reflects emergent structural divergence during decomposition. These results suggest that electrolyte additives function as pathway selectors during early interfacial reaction, offering a framework for rational electrolyte design.

Ultrathin nanoporous membranes based on two-dimensional materials, including molybdenum disulfide (MoS2), offer excellent separation efficiency and chemical stability, making them promising candidates for water purification. Prior molecular dynamics (MD) simulations of MoS2 membranes assumed bare edge structures, neglecting functionalization arising from aqueous environments, due to the lack of suitable classical force fields. Here, we employ quantum-mechanical density functional theory (DFT) to conduct ab initio molecular dynamics simulations that elucidate the interfacial chemistry of MoS2 nanopores in water. Our results reveal a propensity for shape-dependent functionalization at molybdenum (Mo) and sulfur (S) edges of nanopores in MoS2. We observe a pronounced preference in hexagonal pores for hydrogenation (H) at S-terminated edges and oxo (O) functionalization at Mo sites. In contrast, triangular pores with Mo-exposed edges favor hydroxylation (OH), while S-terminated triangular pores remain inert, exhibiting no functionalization. These insights guide the development of accurate, transferable force fields for H-, O-, and OH-functionalized MoS2 nanopores, derived from DFT-computed potential energy surfaces. The resulting models enable stable, chemically realistic MD simulations of molecular and ion transport through MoS2 nanopores harboring various functional groups. Our findings highlight the significant role of edge chemistry in modulating nanoscale transport phenomena. We demonstrate that unfunctionalized S-terminated triangular pores, along with functionalized hexagonal pores, offer high water permeance while maintaining excellent salt and boron rejection, highlighting their potential as promising candidates for selective desalination membranes. Overall, this work offers a robust framework for modeling functionalized MoS2 nanopores in aqueous environments, advancing their application in separation, sensing, and nanofluidic technologies.

Using glycine as a model system, this study examines the surface assisted reaction between methylamine and formic acid on an olivine (010) surface. A comparative analysis of co-adsorbed, mixed phase, and gas phase pathways of methyl amine and formic acid to form glycine shows that a surface assisted pathway exists that connects adsorbed formic acid and methylamine to a surface stabilized glycine configuration with significantly reduced reaction energetics relative to gas phase, suggesting a plausible role for silicate minerals in facilitating complex organic synthesis under astro-physically relevant conditions. First-principles density functional theory calculations were performed using the Vienna Ab initio Simulation Package (VASP) with the Perdew-Burke-Ernzerhof (PBE) exchange correlation functional and the projector augmented wave (PAW) method. Minimum energy reaction pathways and activation barriers were determined using the nudged elastic band (NEB) method, with all energies referenced to clearly defined initial states. Short time thermal stability of surface-bound glycine was assessed using ab initio molecular dynamics (AIMD) simulations at 1200K to probe high temperature persistence on picosecond timescales.

We present a systematic investigation of electronic and optical properties of the AsP/MoSi2P4 van der Waals heterostructure (vdWH) using first-principles calculations. Among six possible stacking configurations, the AA and AB structures are predicted to be the most energetically favorable nanostructures based on binding energy calculations. The ab initio molecular dynamics simulations further confirm the thermal stability of these heterostructures at room temperature. Both AA and AB configurations exhibit semiconducting behavior, with band gaps of 0.712 eV and 0.710 eV, corresponding to type-I and type-II band alignments, respectively. Furthermore, strain engineering is applied to tune the electronic properties of the heterostructures. The band gaps of both stackings can be effectively modulated from 0 to 0.75 eV under vertical strain ranging from -0.2 Å to -1.0 Å. In addition, the uniaxial strain induces transition between direct and indirect band gaps for both stackings. The calculated optical properties demonstrate that both stacking configurations of the AsP/MoSi2P4 vdWH possess significantly enhanced visible-light absorption compared with their constituent monolayers, with a notable power conversion efficiency (PCE) of 17.03% achieved under -4% compressive strain in the AA stacking. Our study provides a comprehensive understanding of the electronic and optical behavior of the AsP/MoSi2P4 heterostructure, highlighting the effects of stacking order and mechanical strain, thereby offering valuable insights for the design of optoelectronic devices.

Proton transfer (PT) kinetics through the electric double layer is a critical yet often overlooked bottleneck for acidic oxygen evolution reaction (OER) under industrially relevant high potential conditions. Herein, we propose an interfacial water microenvironment engineering strategy to address this challenge by constructing a CdO-Co3-x Cd x O4 heterostructure with a strong built-in electric field. Combined in situ ATR-SEIRAS, kinetic isotope effect (KIE) analysis, and ab initio molecular dynamics (AIMD) simulations reveal that the induced electric field effectively disrupts the rigid interfacial hydrogen-bond network, increasing the proportion of isolated water molecules. Crucially, this disordered water structure significantly lowers the energy barrier for water reorientation, thereby directly accelerating the rate-determining proton transfer kinetics. As a result, the catalyst exhibits an order-of-magnitude enhancement in intrinsic activity at 1.70 V vs. RHE compared to pure Co3O4. This work establishes the rational engineering of the interfacial H-bond network as a decisive strategy for overcoming the kinetic limitations of high-potential electrocatalysis.

To address environmental pollution and sustainable energy challenges, lead-free Ag-Bi double perovskites Cs2AgBiX6 (X = Cl, Br) and their ammonium-substituted variants CsNH4AgBiX6 and (NH4)2AgBiX6 are investigated using first-principles FP-LAPW calculations within density functional theory. Ammonium incorporation slightly reduces lattice size while enhancing structural flexibility. Band-structure analysis (GGA, SOC, hybrid-PBE) shows decreasing band gaps with NH4 doping from 2.52 eV to 2.09 eV, with the CBM dominated by Bi states and the VBM by halide p states. Effective mass calculations indicate high carrier mobility due to the low effective mass of (NH4)2AgBiX6 (X = Cl, Br) compared to Cs-based double perovskites, which results in values that are between 0.524 and 0.939 eV, and values that are between 1.2 and 1.645 eV. The stability of these compounds is confirmed through mechanical (C ij ), formation of enthalpy ΔH f and Goldschmidt tolerance factor (τ G) analyses. The elastic constants confirm the mechanically stable and ductile nature of these materials. Furthermore, ab initio molecular dynamics simulations and phonon band-structure calculations have been performed and confirm the stability of the materials. Optical properties reveal stronger light absorption (∼45 × 104 cm-1 in the visible region) and an enhanced dielectric response after NH4 + substitution. Band-edge alignment analysis supports the potential for photocatalytic water splitting, while SLME analysis identifies (NH4)2AgBiBr6 (η max = 6.47%) as the most promising photovoltaic absorber. Overall, A-site ammonium engineering effectively tunes the structural, electronic, optical, and photocatalytic properties of Ag-Bi double perovskites for energy applications.

Lead-free fluoride double perovskites have emerged as promising candidates for stable and environmentally benign optoelectronic applications. In this work, a comprehensive first-principles and device-level investigation of A2AgRhF6 (A = K, Rb, Cs) double perovskites is performed using density functional theory (DFT) within the CASTEP framework, combined with SCAPS-1D solar cell simulations. Structural optimization confirms cubic phase stability with a systematic lattice expansion from K to Cs, while negative formation energies verify thermodynamic stability. Electronic structure analysis reveals direct band gap semiconducting behavior, with band gaps decreasing along the series due to enhanced lattice expansion and modified d-p hybridization. Effective mass calculations indicate improved electron transport with increasing A-site ionic radius, whereas hole transport remains nearly composition-independent. Optical investigations demonstrate strong ultraviolet absorption, moderate visible-light activity, high dielectric response, and pronounced plasmonic features, highlighting their suitability for UV optoelectronic and photonic applications. Charge density and population analyses reveal dominant ionic character of A-site cations and strong covalent Rh-F/Ag-F interactions, confirming that the electronic structure is primarily governed by the AgRhF6 octahedral framework. Mechanical stability is verified through elastic constants satisfying Born criteria, while anisotropy analysis demonstrates moderate directional dependence of elastic behavior. Ab initio molecular dynamics (AIMD) simulations further confirm thermal stability at elevated temperatures, validating structural robustness under operating conditions. Device simulations under AM1.5G illumination demonstrate promising photovoltaic performance with optimized absorber thickness and doping concentration, where Cs2AgRhF6 exhibits the highest power conversion efficiency among experimentally feasible compositions. This combined DFT-device-level study establishes a direct correlation between intrinsic bonding, mechanical stability, thermal robustness, and photovoltaic performance, positioning A2AgRhF6 double perovskites as promising candidates for stable lead-free solar energy conversion and advanced optoelectronic devices.

The long-term stabilization of heavy metals in contaminated soils remains a critical research focus in the field of environmental remediation. Layered double hydroxides (LDHs), owing to their structural tunability and favorable mineralization stability, have demonstrated great potential for the super-stable immobilization of heavy metal ions. In this work, Mg2CaMIII-CO3-LDHs (M = Al,Fe,Mn) models were constructed to systematically investigate the adsorption, co-adsorption, and isomorphic substitution behaviors of Pb2+, Cd2+, and Cu2+, thereby elucidating the super-stable mineralization mechanism from both thermodynamic and kinetic perspectives. Based on density functional theory (DFT) calculations coupled with ab initio molecular dynamics (AIMD) simulations, the results reveal that ternary LDHs exhibit lower activation barriers for adsorption and isomorphic substitution, alongside more stable adsorption configurations, more favorable thermodynamics, and superior co-adsorption capability compared to binary LDH systems. Meanwhile, the coexistence of Mg2+ and Ca2+ provides two distinct substitutable sites within the layers, enabling heavy metals to replace either cation and thus enhancing site selectivity. In addition, in ternary LDHs with Fe as the trivalent cation, increasing the proportion of Ca2+ in the layers enhances the adsorption strength toward all three heavy metal ions, while the introduction of Ca vacancies significantly reduces the energy barriers for isomorphic substitution. Overall, multi-cation synergistic regulation within the layered structure optimizes substitution kinetics while preserving thermodynamic stability, diversifying the mineralization pathways and providing theoretical guidance for the rational design of LDH-based materials for complex remediation systems.

Hydrogen diffusion plays a key role in hydrogen-metal interactions and is closely linked to embrittlement in steels. In iron-based alloys, the influence of local atomic environments on hydrogen diffusion is well recognized, whereas the role of alloy composition remains unclear. Fe-Cr binary alloys, therefore, provide a simple and well-defined model system to isolate the effect of Cr on hydrogen diffusion in iron lattices. In this work, hydrogen diffusion in Fe-Cr alloys is investigated using first-principles calculations based on density functional theory. Ab initio molecular dynamics simulations are further employed to evaluate the influence of Cr concentration on hydrogen diffusion coefficients. The results show that hydrogen diffusion in Fe-Cr alloys is strongly suppressed compared with bcc Fe. This suppression is primarily attributed to higher migration energy barriers resulting from strong Fe-Cr interactions and more compact local atomic packing. Charge transfer analysis demonstrates that hydrogen behaves as an electron acceptor, and the amount of charge transferred is inversely related to the migration barrier. In the disordered solid-solution models, the hydrogen diffusion coefficient decreases with increasing Cr content in the low-Cr range, whereas in the ordered alloy models it exhibits a non-monotonic dependence on composition, with a minimum near 25 at. % Cr. These results reveal the electronic and structural origins of composition-dependent hydrogen diffusion in Fe-Cr alloys at the atomic scale.

Reclamation of emulsified waste organic solvents through filtration adsorption using an under-liquid superlyophilic wood membrane.

• The hydrides X 2 YAlH 6 (X = Rb, Cs; Y = Li, Na, K) were systematically examined using density functional theory calculations. • Thermodynamic analyses and elastic property evaluations confirm that all the hydrides are both thermodynamically and mechanically stable. • The absence of imaginary frequencies in the phonon dispersion spectra verifies the dynamical stability of the hydrides. • Mechanical property analysis indicates that all investigated hydrides exhibit brittle behavior. • Electronic and optical studies reveal that each hydride is a semiconducting material with pronounced absorption in the ultraviolet region. This study investigates the structural, electronic, optical, mechanical, thermodynamic, and hydrogen storage properties of X 2 YAlH 6 (X = Rb, Cs; Y = Li, Na, K) perovskites using the first-principles method. Within the Fm 3 ¯ m space group, all six compounds demonstrate thermodynamic stability, as is verified by their calculated formation energies. The phonon dispersion analysis reveals that five hydrides - Rb 2 LiAlH 6 , Rb 2 NaAlH 6 , Rb 2 KAlH 6 , Cs 2 NaAlH 6 , and Rb 2 KAlH 6 - demonstrate dynamic stability, while Cs 2 LiAlH 6 shows the presence of soft modes. Ab initio molecular dynamics (AIMD) simulations were conducted to evaluate the thermal stability at room temperature. The exchange–correlation is approached using two different approximations - PBE-GGA, and HSE06 to analyze and compare the electronic properties of X 2 YAlH 6 . The calculated elastic constants fulfilled Born’s stability criteria, confirming the mechanical stability of the investigated hydrides. The optical properties showed that X 2 YAlH 6 compounds exhibit peak absorption in the ultraviolet range. The gravimetric hydrogen storage capacity has reached 2.87 wt% for Rb 2 LiAlH 6 , 2.67 wt% for Rb 2 NaAlH 6 , 2.49 wt% for Rb 2 KAlH 6 , 1.98 wt% for Cs 2 LiAlH 6 , 1.88 wt% for Cs 2 NaAlH 6 , and 1.79 wt% for Cs 2 KAlH 6 . Rb 2 LiAlH 6 perovskite is found to have the superior performance out of the materials studied, rendering it a suitable and reliable option for sustained hydrogen storage as a fuel.

Impact of oxidative aging on asphaltene interfacial behavior and emulsion stability: Implications for water remediation.

ABSTRACT This study utilizes first-principles functional theory to investigate a series of newly designed XTiH3 (X = Al, Ga, In, Tl) perovskites. The calculated negative formation energies for the entire series confirm their thermodynamic stability. Comprehensive thermodynamic evaluations, further supported by Ab Initio Molecular Dynamics (AIMD) simulations at 300 K, validate the thermal robustness and structural integrity of these hydrides. Electronic structure analysis reveals a consistent metallic electronic behavior supported by both GGA-PBE and HSE06 functionals. This nature is characterized by a finite total density of states at the Fermi level, where the primary DOS contribution arises from strong hybridization between Ti-3d and H-1s orbitals. Mechanical assessments demonstrate that all compounds satisfy the Born stability criteria, exhibiting ductile character and resistance to deformation. Furthermore, the investigation into optical properties reveals intense absorption in the visible and UV regions, indicating these materials are suitable for use in UV photodetector. Regarding hydrogen storage applications, the gravimetric capacities are 3.88 wt.%, 2.51 wt.%, 1.83 wt% and 1.18 wt.% for AlTiH3, GaTiH3, InTiH3, and TlTiH3, respectively. The desorption temperatures and volumetric capacities for all compounds lie within the range of (703–760) K and (91.2–113.3) gH2/L, respectively.

Rare-earth oxide-phosphates (historically termed oxyphosphates) occupy the compositional space between RE2O3 and REPO4 and form during REPO4 melting and high-temperature degradation of REPO4-based environmental barrier coatings. For several reported stoichiometries, reliable structural models remain unavailable because these phases are low-symmetry, large-unit-cell compounds that seldom form crystals suitable for single-crystal X-ray diffraction. Here, we predict the crystal structure of the compounds reported in the literature as "RE8P2O17" (RE: Sm to Lu, Y) by combining finite-temperature ab initio molecular dynamics (AIMD) simulations with targeted experiments. Syntheses and electron microprobe analysis show the correct RE:P ratio is 3.5, corresponding to RE14P4O31 (14:4). Starting from the melt, AIMD simulations in the SLUSCHI framework, followed by symmetry-constrained relaxation, yield a complex (62 distinct oxygen sites on general positions), monoclinic Pc structure which represents a hitherto unknown structure type. It can be described as a defect fluorite (bixbyite, C-type RE2O3) structure penetrated along one direction by tunnels containing (PO4) tetrahedra. The structure was initially predicted for Y14O15(PO4)4 and was validated for RE = Sm, Eu, Gd, Tb, and Y against synchrotron or laboratory X-ray powder diffraction patterns. Extending the model across the rare-earth series yields consistent lattice trends and places all oxide-phosphates RE14O15(PO4)4 within 46 meV/atom of the 0 K convex hull. A finite-temperature free-energy analysis from MD trajectories predicts entropy stabilization of Y14O15(PO4)4 above ~1,305 K, reconciling metastability at 0 K with observed synthesis and helping resolve discrepancies among published Y2O3-YPO4 phase diagrams.

One of the long-term goals of catalysis is to clarify and understand structure-function relationships. In this work, hydrophilicity of the θ-Al2O3 surface is simulated. The results show sustained H2O/OH adsorption at unsaturated Al sites on the thermodynamically stable θ-Al2O3(010) surface. Furthermore, the multilayer water-covered (010) surface, which possesses highly stable -OH groups, was simulated using ab initio molecular dynamics simulations for modeling surface hydroxylation, and also shows a dynamic proton transfer process. Finally, the infrared vibrational characteristics of the hydroxylated θ-Al2O3 surface were analyzed by using atomic velocity autocorrelation functions and vibrational density of states to determine the structure of the (010) surface, which provides valuable guidance for understanding the hydroxylated θ-Al2O3 catalysts.

Resolving the microscopic structure of the electric double layer remains a significant challenge. To overcome this, we developed a temporal-spatial perspective analytical framework using constant-charge ab initio molecular dynamics simulations, enabling quantitative assessment of the coupling between the interfacial water structure and interfacial polarization response. Four metals, Au, Ag, Cu, and Pt, were selected to systematically probe how intrinsic metal affinities regulate interfacial water organization. The simulations reveal that these metal surfaces induce hydrogen bond networks ranging from loose-disordered to compact-highly ordered, yielding different polarization behaviors. The Ag-H2O interface maintains cooperative polarization while allowing orientational reconfiguration, resulting in the highest interfacial polarization sensitivity. In contrast, the Au-, Cu-, and Pt-H2O interfaces exhibit suppressed tunability due to overly loose or dense hydrogen bond structures. Through systematic comparison, we propose a structure-dynamics cooperative balance mechanism, in which interfacial polarization responsiveness is jointly governed by the dynamic fluctuations of water molecules and the spatial continuity of the hydrogen bond network. This framework offers a new theoretical basis for deepening the microscopic understanding of the electric double layer and guiding interfacial modulation.

Fragmentation of ionic liquid propellants is a major obstacle to achieving the designed performance for electrospray thrusters. This paper investigates the basic electronic properties and fragmentation processes of 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF4) and its constituents by performing quantum-chemistry calculations using the Q-Chem software package, which then informed collision simulations. The calculations characterized optimized molecular structures for monomers, dimers, and the neutral pair, both with and without applied electric fields. Ab initio molecular dynamics simulations of ions in the acceleration region, focusing on collisions, were then performed. Thousands of simulations were carried out to investigate the collision dynamics under electrospray-relevant field strengths, velocities, and impact parameters, emphasizing dissociation and subsequent post-collision dynamics. Across impact parameters b = 0 to 6Å and relative velocities of 5 and 20 km/s, deflection distribution functions show a monotonic shift to higher deflection angles as b decreases. Investigations into final velocity magnitude resolve distinct incident and target populations that converge by b ≤ 2Å, indicating strong momentum exchange in central impacts. In negative mode, peak intensities decrease approximately exponentially along BF4-→BF3→BF2→BF due to sequential fluorine loss. In positive mode, proton availability and cationic bond energetics favor EMI+→C2H5++NMI and elevate H+. Ionic fragmentation dominates at 5 km/s, whereas covalent bond cleavage is most prevalent at 20 km/s. The results clarify the fragmentation pathways and the composition of reaction products, which provide necessary inputs for multiscale assessments of thruster performance.

Roaming reactions-nonstatistical pathways that bypass conventional transition states-were first discovered in photochemistry and were later shown to influence decomposition mechanisms under high-energy conditions relevant to combustion and atmospheric chemistry. Recent work has further revealed that roaming is often enabled by transient, energetically quasi-integrable states emerging within nonequilibrium energy distributions, where fragment motions become dynamically decoupled and intramolecular energy redistribution is strongly suppressed. Building on this perspective, we investigate an ionization-triggered roaming process in the CH4 + CO system that leads to the formation of an acetaldehyde cation (CH3CHO+). Using high-level electronic structure calculations and ab initio direct molecular dynamics (AIMD) simulations, we show that ionization generates a strongly perturbed complex in which the internal energy is partitioned unevenly among its fragments. Rather than following the minimum-energy reaction coordinate, the system enters a dynamically decoupled intermediate, in which the motions of CH3 and HCO+ become dynamically isolated. This transient quasi-integrable state suppresses intramolecular energy redistribution, stabilizing a long-lived roaming configuration characterized by large-amplitude relative fragment motion. This dynamical regime enables C-C bond formation to yield an acetaldehyde cation without passing through conventional isomerization transition states. These results demonstrate that ionization can create roaming-accessible, energetically quasi-integrable regimes even in small molecular systems that are often assumed to follow statistical behavior. The findings further suggest that ionization-driven, roaming-mediated reactions may provide a possible pathway to complex organic ions in cold, low-density astrophysical environments. However, the present simulations do not include radiative cooling or collisional stabilization, and the astrophysical relevance of this mechanism therefore remains speculative.

We report a first-principles study of a novel two-dimensional carbon allotrope, termed Dewar-Octa-Decagraphene (DOD-graphene), and evaluate its potential as a solid-state hydrogen carrier upon lithium functionalization. The pristine monolayer is metallic and dynamically stable. It remains intact during ab initio molecular dynamics (AIMD) at 300 K. Single-atom adsorption shows that Li binds strongly at the centers of the decagonal pores (-2.97 eV) and donates ∼0.8 e to the π network. A fully saturated configuration with two Li per decagon preserves metallicity and withstands AIMD at room temperature. Successive adsorption of up to 20 H2 molecules (7.52 wt %) yields average binding energies ranging from -0.30 to -0.20 eV, which are optimal for reversible storage without dissociation. Thermodynamic isotherms predict full capacity at 300 K under ∼10 atm. At the same time, AIMD simulations confirm rapid desorption: most H2 molecules leave the surface within 3 ps at 300 K without compromising structural integrity. Projected density of states, charge-density difference, and reduced density gradient analyses reveal negligible charge transfer to H2 and identify van der Waals interactions mediated by Li+ centers. The combination of robust Li anchoring, high gravimetric capacity, and facile, physisorptive release positions Li-decorated DOD-graphene as a promising candidate for next-generation hydrogen storage media.