Search

In this work, we systematically explore the effect of four-phonon (4ph) scattering on the lattice thermal conductivity (κ l) of γ -graphyne based on the atomic cluster expansion potential for carbon (C-ACE) combined with a phonon Boltzmann transport equation. The reliability of C-ACE in assessing the thermal transport properties of γ -graphyne is confirmed through comparing the results of phonon dispersion relation and κ 3 p h (only considering 3ph scattering) derived from C-ACE and density functional theory calculations. Regular residual analysis indicates that there might exist a strong 4ph interaction in γ -graphyne, and calculations further demonstrate κ 3 p h + 4 p h (considering 3ph scattering in an iterative solution and 4ph scattering in relaxation time approximation) is indeed reduced by 69.8% relative to κ 3 p h . From the analysis of scattering rates in γ -graphyne, one can intuitively observed that the 4ph scattering occupies a highly significant position in total phonon scattering, which greatly suppresses the κ l. The strong 4ph scattering in γ -graphyne is primarily due to the reflection symmetry selection rule less restricts 4ph scattering process for an out-of-plane flexural acoustic mode. The findings presented in this work demonstrate the reliability of C-ACE based accelerated calculations on the κ l of γ -graphyne, as well as reveal that the strong 4ph scattering in γ -graphyne significantly reduces its κ l , which will greatly promote the application of γ -graphyne and graphyne family in the field of thermoelectricity. [ABSTRACT FROM AUTHOR]

Large-scale atomistic molecular dynamics (MD) simulations provide an exceptional opportunity to advance the fundamental understanding of carbon under extreme conditions of high pressures and temperatures. However, the fidelity of these simulations depends heavily on the accuracy of classical interatomic potentials governing the dynamics of many-atom systems. This study critically assesses several popular empirical potentials for carbon, as well as machine learning interatomic potentials (MLIPs), in their ability to simulate a range of physical properties at high pressures and temperatures, including the diamond equation of state, its melting line, shock Hugoniot, uniaxial compressions, and the structure of liquid carbon. Empirical potentials fail to accurately predict the behavior of carbon under high pressure–temperature conditions. In contrast, MLIPs demonstrate quantum accuracy, with Spectral Neighbor Analysis Potential (SNAP) and atomic cluster expansion (ACE) being the most accurate in reproducing the density functional theory results. ACE displays remarkable transferability despite not being specifically trained for extreme conditions. Furthermore, ACE and SNAP exhibit superior computational performance on graphics processing unit-based systems in billion atom MD simulations, with SNAP emerging as the fastest. In addition to offering practical guidance in selecting an interatomic potential with a fine balance of accuracy, transferability, and computational efficiency, this work also highlights transformative opportunities for groundbreaking scientific discoveries facilitated by quantum-accurate MD simulations with MLIPs on emerging exascale supercomputers. [ABSTRACT FROM AUTHOR]

We present an Atomic Cluster Expansion (ACE) machine learned potential developed for high-fidelity atomistic simulations of hydrocarbons, targeting pressures and temperatures near and above supercritical fluid regimes for molecular fluids. A diverse set of stoichiometries were covered in training, including 1:0 (pure carbon), 1:4 (methane), and 1:1 (benzene), and rich bonding environments sampled at supercritical temperatures, hydrogen rich, reactive mixtures where metastable stoichiometries arise, including 1:2 (ethylene) and 1:3 (ethane). A high-fidelity training database was constructed by performing large-scale quantum molecular dynamic simulations [density functional theory (DFT) MD] of diamond, graphite, methane, and benzene. A novel approach to selecting structures from DFT MD is also presented, which allows for the rapid selection of unique DFT MD frames from complex trajectories. Comparisons to DFT and experimental data demonstrate that the presented ACE potential accurately reproduces isotherms, carbon melting curves, radial distribution functions, and shock Hugoniots for carbon and hydrocarbon systems for pressures up to 100 GPa and temperatures up to 6000 K for hydrocarbon systems and up to 9000 K for pure carbon systems. This work delivers a potential that can be used for accurate, large-scale simulations of shocked hydrocarbons and demonstrates a methodology for fitting and validating machine learning interatomic potentials to complex molecular environments, which can be applied to energetic materials in future works. [ABSTRACT FROM AUTHOR]

Atomistic simulations often rely on interatomic potentials to access greater time and length scales than those accessible to first-principles methods, such as density functional theory. However, since a parameterized potential typically cannot reproduce the true potential energy surface of a given system, we should expect a decrease in accuracy and increase in error in quantities of interest calculated from these simulations. Quantifying the uncertainty on the outputs of atomistic simulations is thus an important, necessary step so that there is confidence in the results and available metrics to explore improvements in said simulations. Here, we address this research question by forming ensembles of atomic cluster expansion potentials, and using conformal prediction with ab initio training data to provide meaningful, calibrated error bars on several quantities of interest for silicon: the bulk modulus, elastic constants, relaxed vacancy formation energy, and the vacancy migration barrier. We evaluate the effects on uncertainty bounds using a range of different potentials and training sets. [ABSTRACT FROM AUTHOR]

Nanoscale magnesium clusters are important potential hydrogen storage materials, and density functional theory (DFT) is mainly used for their theoretical investigation. The results of the coupled-cluster theory at the singles and doubles level with a perturbative treatment of triples [CCSD(T)] were employed previously to choose proper exchange–correlation (XC) functionals in DFT calculations for magnesium clusters, but it is too expensive to be applied to Mgn with n > 7. The diffusion Monte Carlo (DMC) method is employed in this work to study magnesium clusters up to nanosize. The error of atomization energies with DMC using single-determinant-Jastrow (SDJ) trial wavefunctions has been shown to be somewhat larger than that of CCSD(T) for many molecules. However, cohesive energies with DMC using SDJ for Mgn with n ≤ 7 are in excellent agreement with those of CCSD(T) using the aug-cc-pVQZ basis set, with a difference of less than 1 kcal/mol. DMC results are employed to investigate the performance of different XC functionals on magnesium clusters. Our results indicate that the PBE0 functional is the best XC functional for determining the lowest-energy isomer when compared with DMC results, while the RPBE functional is the best XC functional for calculating cohesive energies per atom of these magnesium clusters with a mean absolute error of 0.5 kcal/mol. These XC functionals are expected to provide reasonable results for even larger magnesium clusters. [ABSTRACT FROM AUTHOR]

The configurations, electronic, and magnetic properties of the H2DBP-M clusters have been investigated via density functional theory. The results reveal that the TM atoms for the H2DBP-M (M = Sc , Y, Zr, Nb, Lu, and Hf) clusters deviate from the center planes of the clusters. The H2DBP-M (M = Sc , Y, and Lu) clusters display the largest dipole magnitudes. Based on the binding energy per atom and HOMO-LUMO gap, the H2DBP-Ni and H2DBP-Lu clusters are the most favorable for synthesis. The charge transfer amounts of the TM (TM = Sc , Zn, Y, Cd, Hf, and Hg) atoms for the H2DBP-M clusters are larger. The TM-d orbitals of the H2DBP-M (M = Ti ∼ Co and Cu) clusters contribute significantly to the Fermi levels. The spin densities of the TM atoms for the H2DBP-M clusters reduce to 0 except for that (V = 2. 4 5 9 | e |) of the H2DBP-V clusters. [ABSTRACT FROM AUTHOR]

Hydrogen storage has been a bottleneck factor for the application of hydrogen energy. Hydrogen storage capacity for titanium-decorated boron-doped C20 fullerenes has been investigated using the density functional theory. Different boron-doped C20 fullerene absorbents are examined to avoid titanium atom clustering. According to our research, with three carbon atoms in the pentagonal ring replaced by boron atoms, the binding interaction between the Ti atom and C20 fullerene is stronger than the cohesive energy of titanium. The calculated results revealed that one Ti atom can reversibly adsorb four H2 molecules with an average adsorption energy of −1.52 eV and an average desorption temperature of 522.5 K. The stability of the best absorbent structure with a gravimetric density of 4.68 wt% has been confirmed by ab initio molecular dynamics simulations. These findings suggest that titanium-decorated boron-doped C20 fullerenes could be considered as a potential candidate for hydrogen storage devices. [ABSTRACT FROM AUTHOR]

Direct seawater zinc‐air batteries (S‐ZABs), with their inherent properties of high energy density, intrinsic safety, and low cost, present a compelling avenue for the development of energy storage technology. However, the presence of chloride ions in seawater poses challenges to their air electrode, resulting in sluggish reaction kinetics and poor stability for the oxygen reduction reaction (ORR). Herein, Fe atomic clusters (ACs) decorated Fe single‐metal atoms (SAs) catalyst (FeSA‐FeAC/NC) is prepared using a plasma treatment strategy. The aberration‐corrected transmission electron microscope images confirm the successful construction of Fe SAs surrounding Fe ACs, which delivers robust ORR activity with a half‐wave potential of 0.886 V in alkaline seawater electrolyte. When utilized as the cathode catalyst in assembled S‐ZABs, the battery demonstrates excellent discharge performance, achieving a peak power density of 222 mW cm−2, which is 2.3 times higher than Pt/C based S‐ZABs. Moreover, density functional theory calculations unveil that the synergy effect between the Fe ACs and SAs not only reduces the spin‐down d‐band center in the Fe SAs, but also efficiently suppresses Cl−1 adsorption on Fe SAs due to their strong Cl−1 absorption ability of the Fe ACs, thereby enhancing both the activity and stability of the catalyst. [ABSTRACT FROM AUTHOR]

Single atom alloy (SAA) clusters formed by anchoring single atoms in small supported host clusters are emerging as catalysts with high performance. In this work, density functional theory (DFT) calculations and ab‐initio molecular dynamics (AIMD) simulations are performed to study the stability and the structure evolution of γ‐alumina‐supported platinum/copper SAA clusters of sub‐nanometer size in hydrogen environment. Due to the strong dynamic nature of both Cu cluster and anchored Pt single atom and their evolving interaction with the support, different isomers with different geometric and energetic properties are predicted. Extensive sampling through AIMD simulations reveals strong effect of hydrogen on the location of Pt single atom and strong variation of the cluster shape, evolving from 3D to concave and planar shapes wetting the alumina support. Interfacial site location of Pt single atom is found to be hydrogen coverage dependent. When the hydrogen coverage increases, the Pt single atom located preferentially at the interfacial site is pulled up by hydrogen atoms toward the upper surface Cu layers. The interaction of Pt/Cu cluster with alumina is predicted to decrease with increasing hydrogen coverage. Finally, electronic structure analysis reveals dramatic effect of hydrogen on the metallic nature of the catalysts. [ABSTRACT FROM AUTHOR]

In this paper, a novel soft template assisted strategy has been constructed to the size-tunable preparation of porous Cu−N−C/Surfactant catalysts successfully. The synergistic effects between the adjacent Cu ACs and atomically dispersed Cu-N 4 are favorable for manipulating the binding energy of O 2 adsorption and intermediates desorption at the atomic interface of catalysts, resulting in an excellent electrocatalytic oxygen reduction reaction (ORR) performance with a faster kinetics for Cu−N−C/F127 comparable to the commercially available Pt/C catalyst. [Display omitted] In this paper, a novel, simple and mild soft template assisted strategy and further carbonization approach has been constructed to the size-tunable preparation of porous Cu−N−C/Surfactant catalysts successfully. Note that the pluronic F127 has a significant influence on the synthesis of porous Cu−N−C/F127 with the atomically dispersed Cu-N 4 and adjacent Cu atomic clusters (ACs) than other surfactants owing to their particular non-ionic structure. By combining a series of experimental analysis and density functional theory (DFT) calculations, the synergistic effects between the adjacent Cu ACs and atomically dispersed Cu-N 4 are favorable for manipulating the binding energy of O 2 adsorption and intermediates desorption at the atomic interface of catalysts, resulting in an excellent electrocatalytic ORR performance with a faster kinetics for Cu−N−C/F127 than those of the Cu−N−C, Cu−N−C/CTAB, Cu−N−C/SDS, and comparable with the commercial Pt/C catalyst. This method not only provides a novel approach for synthesizing highly effective copper based single atom catalysts toward ORR, but also offers an in-depth understanding of the synergisms of adjacent ACs on the Cu single atoms (SAs) for highly effective electrocatalytic ORR and Zn-air Battery. [ABSTRACT FROM AUTHOR]

We developed a method for evaluating the accuracies of the local properties of DFT functionals in detail using a clustering method based on machine learning and structural/electronic descriptors. We generated 36 clusters consistent with human intuition using 30,436 carbon atoms from the QM9 dataset. The results were used to evaluate 13C NMR chemical shifts calculated using 84 DFT functionals. Carbon atoms were grouped based on their similar environments, reducing errors within these groups. This enables more accurate assessment of the accuracy using a specific DFT functional. Therefore, the present atomic clustering provides more detailed insight into accuracy verification. [ABSTRACT FROM AUTHOR]

As a Pt-group element, Pd has been regarded as one of the alternatives to Pt-based catalysts for the hydrogen evolution reaction (HER). Herein, we performed density functional theory (DFT) computations to explore the most stable structures of PdxBy (x = 6, 19, 44), revealed the in situ structural reconstruction of these clusters under acidic conditions, and evaluated their HER activity. We found that the presence of B can prevent underpotential hydrogen adsorption and activate the H atoms on the cluster surface for the HER. The theoretical calculations show that the reaction barrier for the HER on ~1 nm sized Pd44B4 can be as low as 0.36 eV, which is even lower than for the same-sized Pt and Pd2B nanoparticles. The ultra-high HER activity of sub-nanosized PdxBy clusters makes them a potential new and efficient HER electro-catalyst. This study provides new ideas for evaluating and designing novel nanocatalysts based on the structural reconstruction of small-sized nanoparticles in the future. [ABSTRACT FROM AUTHOR]

The first step in comprehending the properties of Au10 clusters is understanding the lowest energy structure at low and high temperatures. Functional materials operate at finite temperatures; however, energy computations employing density functional theory (DFT) methodology are typically carried out at zero temperature, leaving many properties unexplored. This study explored the potential and free energy surface of the neutral Au10 nanocluster at a finite temperature, employing a genetic algorithm coupled with DFT and nanothermodynamics. Furthermore, we computed the thermal population and infrared Boltzmann spectrum at a finite temperature and compared it with the validated experimental data. Moreover, we performed the chemical bonding analysis using the quantum theory of atoms in molecules (QTAIM) approach and the adaptive natural density partitioning method (AdNDP) to shed light on the bonding of Au atoms in the low-energy structures. In the calculations, we take into consideration the relativistic effects through the zero-order regular approximation (ZORA), the dispersion through Grimme's dispersion with Becke–Johnson damping (D3BJ), and we employed nanothermodynamics to consider temperature contributions. Small Au clusters prefer the planar shape, and the transition from 2D to 3D could take place at atomic clusters consisting of ten atoms, which could be affected by temperature, relativistic effects, and dispersion. We analyzed the energetic ordering of structures calculated using DFT with ZORA and single-point energy calculation employing the DLPNO-CCSD(T) methodology. Our findings indicate that the planar lowest energy structure computed with DFT is not the lowest energy structure computed at the DLPN0-CCSD(T) level of theory. The computed thermal population indicates that the 2D elongated hexagon configuration strongly dominates at a temperature range of 50–800 K. Based on the thermal population, at a temperature of 100 K, the computed IR Boltzmann spectrum agrees with the experimental IR spectrum. The chemical bonding analysis on the lowest energy structure indicates that the cluster bond is due only to the electrons of the 6 s orbital, and the Au d orbitals do not participate in the bonding of this system. [ABSTRACT FROM AUTHOR]

Tailoring the electronic and optical properties of nitride‐based alloys for optoelectronic device applications in the ultraviolet and red spectral range has attracted significant attention in recent years. Adding boron nitride (BN) to indium gallium nitride (In,Ga)N alloys can help to control the lattice mismatch between (In,Ga)N and GaN and may thus allow to reduce strain‐related defect formation. However, understanding of the impact of BN on the electronic properties of III‐N alloys, in particular the influence of experimentally observed boron atom clustering, is sparse. This work presents first‐principles calculations investigating the electronic properties of highly mismatched (B,In)N alloys with boron contents between 2% and 7%. Special attention is paid to the impact of the alloy microstructure. While the results show that the lattice constants of such alloys largely agree with lattice constants determined from a Vegard approximation, the electronic structure strongly depends on the local boron atom configuration. For instance, if boron atoms are dispersed throughout the structure and are not sharing nitrogen atoms, the band gap of (B,In)N alloys is largely unaffected and stays close to the gap of pristine InN. However, in the case of boron atom clustering, i.e., when boron atoms are sharing nitrogen atoms, the band gap can be strongly reduced, often leading to a metallic state in (B,In)N alloys. These strong band gap reductions are mainly driven by carrier localization effects in the valence band. Our calculations thus show that the electronic structure of (B,In)N alloys strongly depends on the alloy microstructure and that boron atom clustering plays an important role in understanding the electronic and optical properties of these emerging materials. [ABSTRACT FROM AUTHOR]

To efficiently desorb H2, pure Mgn (n = 4–8) clusters were chosen for the hydrogen evolution reaction with H2O. At the PBE0/def2‐TZVP level and the PBE0‐D3/def2‐TZVP level, the lowest energy structures of Mgn (n = 4–8) clusters and the most stable structures of Mgn@H2O (n = 4–8) complexes were searched in the local region. The transition state was predicted, and then the hydrogen evolution reaction channel was obtained by using the intrinsic reaction coordinate (IRC) to confirm the transition state. To better analyze the hydrogen reaction mechanism, the character of Mgn@H2O (n = 4–8) complexes and MgnO (n = 4–8) clusters, as well as the atomic charge change trend, were investigated using interaction region indicator function analysis (IRI) and natural population analysis (NPA). The reaction effect of Mg4 cluster and H2O is the worst. The energy barrier does, however, progressively lower as the cluster atom count rises, improving the reaction effect. [ABSTRACT FROM AUTHOR]

To delve into the microscopic property variations of the ConMoP(n = 1 ~ 5) cluster, this study employs density functional theory at the B3LYP/def2‐TZVP quantum chemistry level. The paper conducts a comprehensive theoretical analysis of the clusters, examining parameters such as bond lengths, bond angles, electronic localization function (ELF), interaction region indicator function (IRI), independent gradient model based on the Hirshfeld partition, deformation density, electronic space range, chemical hardness and softness, polarizability, and dipole moment. The optimization process reveals 16 stable configurations for the ConMoP(n = 1 ~ 5) cluster, predominantly taking on a steric form. As the cluster size increases, the electronic delocalization of Co atoms intensifies, while the electronic properties of Mo atoms remain relatively stable. Notably, P atoms maintain a high degree of electronic delocalization. The interatomic forces within the clusters predominantly exhibit covalent bonding, with no evident repulsive effects observed between atoms. The bonding between metal atoms in the clusters leans toward a preference for covalent interaction. The degree of dispersion in the clusters increases with their growth, particularly evident in configuration 5‐a, which displays a broader spatial distribution. Configuration 3‐a demonstrates the most favorable activity, showcasing a relatively stable structure. Overall, configuration 3‐a emerges as a focal point for catalytic reactions. This article provides a more comprehensive analysis of the ConMoP(n = 1 ~ 5) cluster, yielding diverse results and enhancing the theoretical understanding of this cluster. [ABSTRACT FROM AUTHOR]

Different transition metal loaded metal–organic frameworks (MOFs) have been extensively studied. However, little literature has been written about alkali and alkali-earth metal-loaded MOFs. In this study, we take the DPyDFP linker used for the construction of MOFs as an example. The structures and electronic properties of alkali metals and alkaline earth metals loaded DPyDFP clusters have been investigated using density functional theory. The results indicate that the structural stability of alkali metals and alkaline earth metals loaded DPyDFP clusters is less than that of transition metals loaded DPyDFP clusters. The interior of the DPyDFP clusters has not enough space to locate a large alkali metal or alkaline earth metal atom except for Li, Be and Mg. It indicates that if the IAM and IIAM atoms are loaded on the linker to build a MOF framework, Li, Be and Mg are worth considering. The DPyDFP-IIAM clusters exhibit more structural stability and chemically stable than corresponding DPyDFP-IAM clusters. The HOMOs and LUMOs of the DPyDFP-IAM and DPyDFP-IIAM clusters mostly surround N and C atoms. The IAM-N and IIAM-N bonds exhibit certain covalent character. Due to the limited charge transfer between the IAM (or IIAM) atoms and the DPyDFP clusters, the IAM (or IIAM) atoms are not a good choice to design the novel linker to build a MOF framework. [ABSTRACT FROM AUTHOR]

One or two phenylacetylide (PA) ligand(s) were successfully removed from the IrAu12 superatomic core of [IrAu12(dppe)5(PA)2]+ (dppe=1,2‐bis(diphenylphosphino)ethane) by reaction with controlled amounts of tetrafluoroboric acid. Optical and nuclear magnetic resonance spectroscopies and density functional theory calculations revealed the formation of open Au site(s) on the IrAu12 core of [IrAu12(dppe)5(PA)1]2+ and [IrAu12(dppe)5]3+ with the remaining structure intact. Isocyanide was efficiently trapped at the open electrophilic site on [IrAu12(dppe)5(PA)1]2+, whereas a dimer or trimer of the IrAu12 superatoms was formed using diisocyanide as a linker. These results open the door to designed assembly of chemically modified metal superatoms. [ABSTRACT FROM AUTHOR]

In this work, density-functional theory (DFT) was used to investigate the geometry and electronic structure of Run(n = 1–6,10) supported on CeO2(110) (Run(n = 1–6,10)/CeO2(110)) and their electrocatalytic properties for the N2 reduction reaction (NRR). The results indicated that there is a strong metal–support interaction between Run and CeO2(110), which leads to large surface distortion and stabilized Run. On Run(n = 1–6,10)/CeO2(110), N2 captured in the end-on mode is thermodynamically more favorable than that captured in the side-on mode; however, the side-on mode can lead to stronger activation of N2 which promotes the following protonation step of N2. For Run(n = 3,5,6)/CeO2(110), the electrochemical NRR prefers to occur via an enzymatic mechanism with limiting potentials of −0.31, −0.53 and −0.66 V. The electrocatalytic activity of Run(n = 1–6,10)/CeO2(110) for the NRR shows a strong size dependence. For Ru3/CeO2(110), it has the lowest absolute value of limiting potential, and with the increase in n (n > 3), the limiting potential becomes more negative. Moreover, Ru3/CeO2(110) shows high selectivity and stability. This study gives valuable insights for designing effective catalysts for the NRR. [ABSTRACT FROM AUTHOR]

It is generally believed that oxygen in NiTi alloys exists only as Ti4Ni2O. In this work, the possibility of interstitial oxygen has been investigated by experiment and modelling. The sintered elemental NiTi alloys with different oxygen contents were prepared to investigate the relationship between the Ni equivalent (Nieq) and peak transformation temperature (Mp). The results showed at the same Nieq, the Mp was considerably higher than the value reported in the literature. The NiTi matrix with different oxygen contents was observed using atomic probes. Oxygen was found to be uniformly distributed throughout the matrix. The number of independent O atoms and Ti–O clusters increased with increasing oxygen content. Density functional theory was used to calculate the solid solution energy and the formation energy of NiTi superlattice with interstitial oxygen. Oxygen could exist stably in the interstices. The formation energy of interstitial oxygen in NiTi[O] was always higher than that of Ti4Ni2O, which suggested Ti4Ni2O may be the final equilibrium state. However, interstitial oxygen is still an important form existed in the non-equilibrium state, such as powder metallurgical NiTi. The results of this study provide a new basis for predicting the Mp of Ni–Ti–O systems. [ABSTRACT FROM AUTHOR]

The search for new superhydrides, promising materials for both hydrogen storage and high temperature superconductivity, made great progress, thanks to atomistic simulations and Crystal Structure Prediction (CSP) algorithms. When they are combined with Density Functional Theory (DFT), these methods are highly reliable and often match a great part of the experimental results. However, systems of increasing complexity (number of atoms and chemical species) become rapidly challenging as the number of minima to explore grows exponentially with the number of degrees of freedom in the simulation cell. An efficient sampling strategy preserving a sustainable computational cost then remains to be found. We propose such a strategy based on an active-learning process where machine learning potentials and DFT simulations are jointly used, opening the way to the discovery of complex structures. As a proof of concept, this method is applied to the exploration of tin crystal structures under various pressures. We showed that the α phase, not included in the learning process, is correctly retrieved, despite its singular nature of bonding. Moreover, all the expected phases are correctly predicted under pressure (20 and 100 GPa), suggesting the high transferability of our approach. The method has then been applied to the search of yttrium superhydrides (YHx) crystal structures under pressure. The YH6 structure of space group Im-3m is successfully retrieved. However, the exploration of more complex systems leads to the appearance of a large number of structures. The selection of the relevant ones to be included in the active learning process is performed through the analysis of atomic environments and the clustering algorithm. Finally, a metric involving a distance based on x-ray spectra is introduced, which guides the structural search toward experimentally relevant structures. The global process (active-learning and new selection methods) is finally considered to explore more complex and unknown YHx phases, unreachable by former CSP algorithms. New complex phases are found, demonstrating the ability of our approach to push back the exponential wall of complexity related to CSP. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) and coupled cluster theory (CCSD(T)) calculations are performed to investigate the geometric and electronic structures and chemical bonding of a series of Cu-doped zinc oxide clusters: CunZn3O3 (n = 1–4). The structural evolution of CunZn3O3 (n = 1–4) clusters may reveal the aggregation behavior of Cu atoms on the Zn3O3 cluster. The planar seven-membered ring of the CuZn3O3 cluster plays an important role in the structural evolution; that is, the Cu atom, Cu dimer (Cu2) and Cu trimer (Cu3) anchor on the CuZn3O3 cluster. Additionally, it is found that CunZn3O3 clusters become more stable as the Cu content (n) increases. Bader charge analysis points out that with the doping of Cu atoms, the reducibility of Cu aggregation (Cun−1) on the CuZn3O3 cluster increases. Combined with the d-band centers and the surface electrostatic potential (ESP), the reactivity and the possible reaction sites of CunZn3O3 (n = 1–4) clusters are also illustrated. [ABSTRACT FROM AUTHOR]

The structures of phosphorus clusters with the number of atoms from 17 to 220 and their stability are studied theoretically. To calculate total energies of clusters a model is used that allows the highly accurate reproduction of density functional theory results. Calculations show that the most energetically favorable clusters Pn with 17 ≤ n ≤ 90 are single-stranded structures. At 91 ≤ n ≤ 125 these systems compete with double strands of fibrous phosphorus, and at n ≥ 126 fibrous phosphorus clusters become more favorable. The application of local stability criteria makes it possible to reveal the most stable clusters that are most likely to occur in the experiment. [ABSTRACT FROM AUTHOR]

The structures of phosphorus clusters with the number of atoms from 17 to 220 and their stability are studied theoretically. To calculate total energies of clusters a model is used that allows the highly accurate reproduction of density functional theory results. Calculations show that the most energetically favorable clusters Pn with 17 ≤ n ≤ 90 are single-stranded structures. At 91 ≤ n ≤ 125 these systems compete with double strands of fibrous phosphorus, and at n ≥ 126 fibrous phosphorus clusters become more favorable. The application of local stability criteria makes it possible to reveal the most stable clusters that are most likely to occur in the experiment. [ABSTRACT FROM AUTHOR]

This article investigates the structural stability and hydrogen adsorption performance of Na-decorated heteroborospherene Si 4 B 32 using density functional theory (DFT) methods. DFT calculations demonstrate that six sodium (Na) atoms can successfully and chemically bind to the surface of heteroborospherene Si 4 B 32 , exhibiting a substantial average binding energy of 2.465 eV without clustering. Moreover, the resulting Na 6 Si 4 B 32 structure retains its integrity even after absorbing up to 30 hydrogen (H 2) molecules, with an average adsorption energy of 0.251 eV/H 2. Utilizing DFT analysis, the gravimetric density of Na 6 Si 4 B 32 ·(H 2) 30 can reach 9.143 wt%. Additionally, employing ab initio molecular dynamics (AIMD) simulations, we find that a significant fraction of the H 2 molecules desorb from Na 6 Si 4 B 32 at 300K within 1000 fs. These findings establish the potential of Na-decorated heteroborospherene Si 4 B 32 as a promising candidate for reversible hydrogen storage. The successful binding of Na atoms without clustering and the substantial H 2 adsorption capacity, coupled with the structural stability and facile H 2 desorption observed at moderate temperatures, highlight the viability of this material for practical hydrogen storage applications. [Display omitted] • The Na atoms can bind on the surface of Si 4 B 32 without metal clustering. • The Na 6 Si 4 B 32 cluster can adsorb up to 30H 2 molecules with a hydrogen storage capacity of 9.143 wt%. • H 2 adsorption energy locates in the range from 0.251 to 0.320 eV/H 2. • Dynamics simulation results verify the reversibility of H 2 storage. [ABSTRACT FROM AUTHOR]

Planar oxide atomic clusters are of considerable scientific interest because of their potential for enhanced catalytic activity versus their three‐dimensional counterparts. This enhancement is the result of the substrate stabilizing novel planar configurations that have an extensive periphery where catalytic reactions can occur. A class of planar NbnOm atomic clusters that are synthesized by the evaporation of metallic Nb onto an Au(111) substrate in an ultrahigh vacuum environment and subsequent oxidation at elevated temperatures is reported. The atomic structures of the clusters are determined using a combination of scanning tunneling microscopy and density functional theory. The clusters are composed of structural units with four‐, five‐, and sixfold rotational symmetry and these units can assemble to form larger planar clusters. The theoretical comparison of supported structures with their hypothetical freestanding counterparts shows that the atomic and electronic structures of the oxide clusters are significantly altered by the interaction with the Au substrate. The substrate effects include interfacial charge transfer and structural relaxation to relieve the strain in the Nb‐O bonds. The substrate interactions also reduce the energy differences between clusters of different configurations and this enables the coexistence of a large variety of cluster configurations. [ABSTRACT FROM AUTHOR]

Recent advancements in experimental approaches have made it possible to synthesize silver (Ag5) atomic quantum clusters (AQCs), which have shown a great potential in photocatalysis. This study employs the generalized gradient approximation (GGA) density functional theory (DFT) to explore the adsorption of CO2, CH4, and H2O molecules on the Ag5 AQC. Our investigations focus on the structural and electronic properties of the molecules in Ag5 AQC systems. This involves adsorption energy simulations, charge transfer, charge density difference, and the density of states for the modelled systems. Our simulations suggest that CH4 and H2O molecules exhibit higher adsorption energies on the Ag5 AQC compared to CO2 molecules. Remarkably, the presence of CH4 molecule leads to a significant deformation in the Ag5 AQC structure. The structure reforms from a bipyramidal to trapezoidal shape. This study also reveals that the Ag5 AQC donates electrons to CO2 and CH4 molecules, resulting in an oxidation state. In contrast, gaining charges from H2O molecules results in a reduced state. We believe the proposed predictions provide valuable insights for future experimental investigations of the interaction behaviour between carbon dioxide, methane, water molecules, and Ag5 sub-nanometre clusters. [ABSTRACT FROM AUTHOR]

Growth pattern and electronic and magnetic properties of AgnCr (n = 1–16) clusters have been investigated via density functional theory (DFT) combined with CALYPSO structure search method. The optimized geometry shows that the growth of the global minimum structures of AgnCr clusters have obvious rule. when n > 12, silver atoms grow around an icosahedron which is almost unchanged in each structure. Analyses of electronic properties indicate that the doped Cr atom can only enhance the stability of larger silver clusters. Optical absorption and photoelectron spectra of AgnCr isomers have been predicted and can be used for their structural identification. The icosahedral Ag12Cr cluster with large energy level gap can be seen as a superatom. The adsorption capacity of Cr atom in AgnCr cluster to CO is much higher than that of free Cr atom. The intensity of IR and Ramam spectra can be dramatically enhanced when CO is absorbed on AgnCr cluster that Cr atom is encapsulated by Ag atoms. Moreover, the red shift of IR and Raman spectra of CO adsorbed on these clusters is also very small compared to free CO. Magnetism calculations show that the magnetic moment of AgnCr clusters decreases linearly from n = 6 to 12 and increases linearly from n = 12 to 16. The total magnetic moment of AgnCr cluster is mainly localized on the Cr atom. The change of magnetic moment of Cr atom is related to the charge transfer between Cr and Ag atoms. [ABSTRACT FROM AUTHOR]

This paper presents results of density functional calculations of the atomic structure and electronic spectrum of (n = 12–17) clusters with the use of three distinct functionals. We analyze how the choice of the functional influences cluster structure optimization results and compare calculated electronic spectra of the most stable cluster isomers with measured photoelectron spectra, which makes it possible to assess the adequacy of the calculation method and identify the structure of the clusters. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) studies are performed on the geometric structures, stability, electronic properties of the RhmPdn (m + n = 13) clusters. All the configurations are 13-atomic icosahedral structures, with an atom in the central site. Rh1Pd12 has Ih symmetry and relatively suitable stability and electronic properties among these clusters, with moderate stability and inter-atomic binding interaction as the representative system for the study of NO molecule adsorption and dissociation. NO molecule tends to be end-on adsorbed on Rh1Pd12 with its N atom connecting to metal atoms of the cluster, preferably at the hollow site to the top or bridge site. For the dissociation of NO as a key step in its reduction, the adsorption and dissociation of NO on Rh1Pd12 cluster are overall exothermic reactions from the energies of the free NO molecule and the cluster. Doping Rh in the pure cluster affects little on the adsorption energy and dissociation energy barrier but much on the relative energy (the energy reduction from the free NO molecule and cluster to the final state). [ABSTRACT FROM AUTHOR]

In this work, the hydrogen storage capability in light metal (Na and K) decorated heteroborospherene C4B32 was investigated by using density functional theory (DFT) calculations. Na atoms can strongly bind to C4B32 with the average binding energy of 2.720 eV. The clusters of Na atoms decorated C4B32 are observed to be structurally stable even after the adsorption of H2 molecules. Each Na atom can adsorb 6H2 molecules with average adsorption energy of 0.199 eV/H2 yielding gravimetric H2 uptake of 8.99 wt%. However, the average adsorption energy of H2 molecules in K4C4B32 is much less than 0.2 eV. Therefore, Na decorated heteroborospherene C4B32 can act as an effective material for reversible H2 storage. • Na and K atoms bind strongly on C 4 B 32 and do not agglomerate together. • K decorated C 4 B 32 is not suitable for H 2 storage due to unqualified adsorption energy. • Na 4 C 4 B 32 stores 24H 2 molecules with average adsorption energy of 0.199 eV/H 2. • The desorption temperature of Na 4 C 4 B 32 ·(H 2) 24 is 289 K. [ABSTRACT FROM AUTHOR]

Context: To comprehend the microscopic property alterations within the ConMoS cluster (n=1–5), this study investigates its internal interactions, electronic characteristics, and orbital correlations employing density functional theory. Structural optimization and theoretical analysis of the cluster are conducted using the Gaussian09 software package, considering various spin multiplicities and employing the B3LYP/def2tzvp quantum chemical method as the computational standard. The outcomes reveal the optimization of the cluster, resulting in 21 stable configurations while continually acquiring energy from the external environment. Analysis of the interaction region indicator functions, the independent gradient model based on Hirshfeld partition, the localized orbital indicator functions, and the electron localization function reveals a trend toward chemical bonding interactions within the interatomic interaction regions. Moreover, the interatomic forces exhibit a high likelihood of engaging in covalent bonding interactions. Both Co and Mo atoms display greater electron delocalization, facilitating the exchange of electrons with the external environment. The paper discuss electron space range, hardness and softness, polarizability, dipole moment, Mulliken population analysis, density of states, HOMO-LUMO diagram, and UV-Vis spectra. Configuration 5a exhibits the broadest electron delocalization and the highest reactivity. It maintains structural stability in external conditions and displays the most polarized molecules. Metal atoms in this cluster exhibit superior mobility compared to non-metal atoms. We elucidate the electron density aggregation region within the cluster. Configuration 1a demonstrates the highest correlation with molar absorption coefficient for its peak. Analyzing the HOMO and LUMO orbital delocalization index and center-of-mass distances revealed that the front orbits of configuration 5a exhibited a broad distribution in space and the minimum center-of-mass distance. Methods: This study presents a theoretical investigation of Co-Mo-S clusters employing density functional theory (DFT). DFT is a prevalent method for exploring the electronic structure and characteristics of atoms, molecules, and solids. The paper examines cluster attributes encompassing interatomic interactions, electronic properties, and frontier orbitals. Gaussian09 software is employed for optimizing cluster structures, while the analysis is augmented using Multiwfn wave function analysis software. By harnessing these theoretical and computational tools, it aims to delve deeper into cluster properties, yielding valuable insights. [ABSTRACT FROM AUTHOR]

Context: Mercaptopurine is an effective anticancer medicine yet known with serious adverse reactions, thus requiring further attempts to enhance its biological targeting. Small gold clusters Aun (n = 2–10) were used as model reactants to simulate the surface of gold nanoparticles. The computed results show that the drug molecules tend to anchor on the gold clusters at the S atom with the associated binding energies varying from −50 to −34 kcal mol−1 (in vacuum) and from −42 to −28 kcal mol−1 (in aqueous solution). Furthermore, the adsorption of the drug onto the gold surface is considered as a reversible process, and the mechanism of drug releasing was found to be triggerable by internal factors, such as a pH change or the concentrated presence of thiol amino acids in cancerous protein structures. Method: Calculations based on density functional theory (DFT) were performed to probe the nature of interactions between the drug and gold nanoparticles. Structural features, thermodynamic parameters, bonding characteristics, and electronic properties of the resulting complexes were investigated at the PBE//cc-pVTZ/cc-pVDZ-PP level. [ABSTRACT FROM AUTHOR]

All electron density functional theory‐based calculations are carried out to investigate the properties of metal/oxide nanostructures taking the case of a Ru13 cluster supported on an octahedral anatase (TiO2)84 nanoparticle, as a representative system. The interaction between both systems is exothermic showing binding energies below −4 eV. In spite of the large interaction, the structure of the (TiO2)84 nanoparticle remains unaltered. However, the metal‐support interaction promotes the deformation of the Ru13 cluster atomic structure. This deformation is more accentuated when the Ru13 nanocluster is situated in the facet region of the (TiO2)84 nanoparticle than when the interaction involves the edge regions. The formation of the Ru13/(TiO2)84 heterostructure leads to a decrease of the energy gap inherent to the bare (TiO2)84 nanoparticle, becoming almost negligible. This is due to the contribution of the partially filled Ru 4d orbitals with Kohn–Sham energies spanning in the energy range of those of the O 2p occupied and Ti 3d empty manifolds. This feature is systematically observes no matter the interaction involves the oxide nanoparticle facet or edge regions. This study constitutes a first step in designing a strategy to investigate metal‐semiconductor nanostructures using realistic models that go beyond the use of extended surfaces. [ABSTRACT FROM AUTHOR]

The atom‐cluster interaction has recently been exploited as an effective way to increase the performance of metal‐nitrogen‐carbon catalysts for oxygen reduction reaction (ORR). However, the rational design of such catalysts and understanding their structure‐property correlations remain a great challenge. Herein, we demonstrate that the introduction of adjacent metal (M)−N4 single atoms (SAs) could significantly improve the ORR performance of a well‐screened Fe atomic cluster (AC) catalyst by combining density functional theory (DFT) calculations and experimental analysis. The DFT studies suggest that the Cu−N4 SAs act as a modulator to assist the O2 adsorption and cleavage of O−O bond on the Fe AC active center, as well as optimize the release of OH* intermediates to accelerate the whole ORR kinetic. The depositing of Fe AC with Cu−N4 SAs on nitrogen doped mesoporous carbon nanosheet are then constructed through a universal interfacial monomicelles assembly strategy. Consistent with theoretical predictions, the resultant catalyst exhibits an outstanding ORR performance with a half‐wave potential of 0.92 eV in alkali and 0.80 eV in acid, as well as a high power density of 214.8 mW cm−2 in zinc air battery. This work provides a novel strategy for precisely tuning the atomically dispersed poly‐metallic centers for electrocatalysis. [ABSTRACT FROM AUTHOR]

The magnetic response of valence electrons in doped gold-based M @ A u 8 L 8 q superatoms (M = Pd, Pt, Ag, Au, Cd, Hg, Ir, and Rh; L = PPh3; and q = 0, +1, +2) is studied by calculating the gauge including magnetically induced currents (GIMIC) in the framework of the auxiliary density functional theory. The studied systems include 24 different combinations of the dopant, total cluster charge, and cluster structure (cubic-like or oblate). The magnetically induced currents (both diatropic and paratropic) are shown to be sensitive to the atomic structure of clusters, the number of superatomic electrons, and the chemical nature of the dopant metal. Among the cubic-like structures, the strongest aromaticity is observed in Pd- and Pt-doped M @ A u 8 L 8 0 clusters. Interestingly, Pd- and Pt-doping increases the aromaticity as compared to a similar all-gold eight-electron system A u 9 L 8 + 1 . With the recent implementation of the GIMIC in the deMon2k code, we investigated the aromaticity in the cubic and butterfly-like M@Au8 core structures, doped with a single M atom from periods 5 and 6 of groups IX–XII. Surprisingly, the doping with Pd and Pt in the cubic structure increases the aromaticity compared to the pure Au case not only near the central atom but encompassing the whole metallic core, following the aromatic trend Pd > Pt > Au. These doped (Pd, Pt)@Au8 nanoclusters show a closed shell 1S21P6 superatom electronic structure corresponding to the cubic aromaticity rule 6n + 2. [ABSTRACT FROM AUTHOR]

The adsorption and dissociation of hydrogen molecule on small PdnAgm (n + m ≤ 4) clusters is studied employing density functional theory (DFT) calculations. The lowest energy structures of the PdnAgm clusters are initially presented. Based on the obtained structures, various geometries of H2 adsorption and dissociation with these clusters are examined. The cluster size and composition of the PdnAgm clusters are found to control the nature of the adsorption process. The results suggest that molecular adsorption is more favorable on the Pd atom and mixed clusters, while hydrogen dissociation is more favorable on the Pdn (n = 2–4) clusters. The Pd dimer and trimer are found to be the most reactive clusters for hydrogen adsorption, while single Ag atom is the least reactive one. The natural bond orbital (NBO) population analysis indicates that hydrogen atoms tend to draw electrons from the metal clusters in the dissociative form and donate electrons to the metal clusters in the molecular adsorption form. The density of states (DOS) of the PdnAgm trimers are also presented and discussed. The interaction and stabilities of cluster on the graphene support has also been performed. [ABSTRACT FROM AUTHOR]

We report two atomically precise alloy nanoclusters of Ag4Rh2(C≡CArF)8(PPh3)2 and Au4Rh2(C≡CArF)8(PPh3)2 (Ar = 3,5-(CF3)2C6H3, abbreviated as Ag4Rh2 and Au4Rh2, respectively) co-protected by alkynyl and phosphine ligands. Both clusters have identical octahedral metal core configurations and can be termed superatoms with two free electrons. However, they possess different optical features, manifested by totally different absorbance peaks, and drastically different emission peaks, and also, Ag4Rh2 has a much higher fluorescence quantum yield (18.43%) than Au4Rh2 (4.98%). Moreover, Au4Rh2 exhibited markedly superior catalytic performance in the electrochemical hydrogen evolution reaction (HER), manifested by a much lower overpotential at 10 mA cm−2 and better stability. Density functional theory (DFT) calculations revealed that the free energy change of Au4Rh2 for the adsorption of two H* (0.64 eV) is lower than that of Ag4Rh2 for the adsorption of one H* (−0.90 eV) after stripping a single alkynyl ligand from the cluster. In contrast, Ag4Rh2 demonstrated much stronger catalytic capability for catalyzing 4-nitrophenol reduction. The present study provides an exquisite example to understand the structure–property relationship of atomically precise alloy nanoclusters, and emphasizes the importance of fine-tuning of the physicochemical properties and catalytic performance of the metal nanoclusters through modulating the metal core and beyond. [ABSTRACT FROM AUTHOR]

L-α-alanine (LαA) is a non-essential α-amino acid in the human body. Free radicals formations in LαA induced by solid-state radiation have been the subject of investigations by electron paramagnetic resonance (EPR) spectroscopy. The Density Functional Theory (DFT) formalism has been used to calculate the EPR parameters of the radiation-induced radicals in the solid-state LαA in this article. Here, the effects of various factors such as the kind of hydrogen bonding (short and long-range) and the temperature have considered to calculate the EPR parameters. An atomic static cluster model has been used to evaluate the short-range hydrogen bonding effects, and Molecular Dynamic (MD) cluster model has been used simultaneously to study the influence of the short-range hydrogen bonding and temperature. A static periodic technique has been used to consider hydrogen bonds (short and long-range) effect. Finally, the MD periodic calculations have been used simultaneously to study the influence of the hydrogen bonds and temperature. These MD periodic calculations are more consistent with experiments than static periodic calculations and clusters. The EPR spectrums of LαA powder and crystal have been simulated and compared with the experimental EPR spectrums. The results show that they are in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

Density Functional Theory calculations are performed to study the adsorption of Li, B, N, and O clusters on graphene and to clarify the interaction of these atoms with a graphene sheet. The stable structures, the adsorption and interaction energies and the Density of States (DOS) of adatom-graphene systems are calculated. The obtained results show that light atoms on graphene are governed by physisorption/chemisorption mechanisms with and without clustering occurrence. More interestingly, the formation of diatomic molecules is noticed. For example, Li atoms prefer to be physisorbed whereas B atoms prefer the clustering configuration on the graphene sheet. For N and O atoms, the molecule formation is preferred to the clustering one. The electronic structure of studied systems is analyzed by performing densities of states calculations. The results show that electronic structures are affected by the increasing concentration and the nature of adsorbed light atoms. [ABSTRACT FROM AUTHOR]

Although the physics and chemistry of materials are driven by exposed surfaces in the morphology, they are fleeting, making them inherently challenging to study experimentally. The rational design of their morphology and delivery in a synthesis process remains complex because of the numerous kinetic parameters that involve the effective shocks of atoms or clusters, which end up leading to the formation of different morphologies. Herein, we combined functional density theory calculations of the surface energies of ZnO and the Wulff construction to develop a simple computational model capable of predicting its available morphologies in an attempt to guide the search for images obtained by field-emission scanning electron microscopy (FE-SEM). The figures in this morphology map agree with the experimental FE-SEM images. The mechanism of this computational model is as follows: when the model is used, a reaction pathway is designed to find a given morphology and the ideal step height in the whole morphology map in the practical experiment. This concept article provides a practical tool to understand, at the atomic level, the routes for the morphological evolution observed in experiments as well as their correlation with changes in the properties of materials based solely on theoretical calculations. The findings presented herein not only explain the occurrence of changes during the synthesis (with targeted reaction characteristics that underpin an essential structure–function relationship) but also offer deep insights into how to enhance the efficiency of other metal-oxide-based materials via matching. [ABSTRACT FROM AUTHOR]

Metal single atoms show outstanding electrocatalytic activity owing to the abundant atomic reactive sites and superior stability. However, the preparation of single atoms suffers from inexorable metal aggregation which is harmful to electrocatalytic activity. Here, ionic covalent organic frameworks (iCOFs) are employed as the sacrificial precursor to mitigate the metal aggregation and subsequent formation of bulky particles. Molecular dynamics simulation shows that iCOFs can trap and confine more Co ions as compared to neutral COFs, resulting in the formation of a catalyst composed of Co single atoms and uniformly distributed Co nanoparticles (CoSA&CoNP‐10). However, the neutral COFs derive a catalyst composed of Co atomic clusters and large Co nanoparticles (CoAC&CoNP‐25). The CoSA&CoNP‐10 catalyst exhibits higher oxygen bifunctional electrocatalytic activities than CoAC&CoNP‐25, coinciding with the density functional theory results. Taking the CoSA&CoNP‐10 as the air cathode in Zn–air batteries (ZABs), the aqueous ZAB presents a high power density of 181 mW cm−2, a specific capacity of 811 mAh g−1 as well as a long cycle life of 407 h at a current density of 10 mA cm−2, while the quasi‐solid state ZAB displays a power density of 179 mW cm−2 and the cycle life of 30 h. [ABSTRACT FROM AUTHOR]

The development of precious‐metal alternative electrocatalysts for oxygen reduction reaction (ORR) is highly desired for a variety of fuel cells, and single atom catalysts (SACs) have been envisaged to be the promising choice. However, there remains challenges in the synthesis of high metal loading SACs (>5 wt.%), thus limiting their electrocatalytic performance. Herein, a facile self‐sacrificing template strategy is developed for fabricating Co single atoms along with Co atomic clusters co‐anchored on porous‐rich nitrogen‐doped graphene (Co SAs/AC@NG), which is implemented by the pyrolysis of dicyandiamide with the formation of layered g‐C3N4 as sacrificed templates, providing rich anchoring sites to achieve high Co loading up to 14.0 wt.% in Co SAs/AC@NG. Experiments combined with density functional theory calculations reveal that the co‐existence of Co single atoms and clusters with underlying nitrogen doped carbon in the optimized Co40SAs/AC@NG synergistically contributes to the enhanced electrocatalysis for ORR, which outperforms the state‐of‐the‐art Pt/C catalysts with presenting a high half‐wave potential (E1/2 = 0.890 V) and robust long‐term stability. Moreover, the Co40SAs/AC@NG presents excellent performance in Zn–air battery with a high‐peak power density (221 mW cm−2) and strong cycling stability, demonstrating great potential for energy storage applications. [ABSTRACT FROM AUTHOR]

This paper presents results of computer simulation experiments based on density functional calculations of the atomic structure and electronic spectrum of (n = 15–17) clusters. Based on the Wade–Mingos rules, we identify general trends in the formation of monoanionic hafnium-doped Sn clusters, which make it possible to optimize prognostic studies concerned with a search for novel nanostructured materials. We compare calculation results obtained with the B3LYP, B3PW91, and PBE functionals in combination with the SDD basis set and analyze the effect of the functionals on atomic structure optimization results. An optimal strategy is proposed for computer simulation experiments dealing with modeling of the spatial structure of Sn-based clusters and confirmed by comparison with available experimental data. [ABSTRACT FROM AUTHOR]

This paper reports the computational study of phosphorus-doped boron clusters PBn/ P B n – / P B n + (n = 4–8). First, a global search and optimization of these clusters were performed to determine the stable structures. We used density functional theory (DFT) methods and ab initio calculations to study the stability of the atomic clusters and to explore the arrangement of stable structures. We found that the lowest energy structures of the smaller phosphorus-doped boron clusters tend to form planar or quasi-planar structures. As additional boron atoms are added to the smallest structures, the boron atoms expand in a zigzag arrangement or in a net-like manner, and the phosphorus atom is arranged on the periphery. For larger structures with seven or eight boron atoms, an unusual umbrella-like structure appears. We calculated the binding energy as well as other energies to study cluster stability. We calculated the ionization energy, electron affinity, and the HOMO–LUMO gaps. In addition, we used the adaptive natural density partitioning program to perform bond analysis so that we have a comprehensive understanding of the bonding. In order to have a suitable connection with the experiment, we simulated the infrared and photoelectron spectra. [ABSTRACT FROM AUTHOR]

Transition metal carbides have been shown to exhibit good catalytic performance that depends on their compositions and morphologies, and understanding such catalytic properties requires knowledge of their precise geometry, determination of which is challenging, particularly for clusters formed by multiple elements. In this study, we investigate the geometries and electronic structures of binary VnC3− (n=1−6) clusters and their neutrals using photoelectron spectroscopy and theoretical calculations based on density functional theory. The adiabatic detachment energies of VnC3−, or equally, the electron affinities of VnC3, have been determined from the measured photoelectron spectra. Theoretical calculations reveal that the carbon atoms become separate when the number of V atoms increases in the clusters, i.e., the C−C interactions present in small clusters are replaced by V−C and/or V−V interactions in larger ones. We further explore the composition dependent formation of cubic or cube-like structures in 8-atom VnCm(n+m=8) clusters. [ABSTRACT FROM AUTHOR]

Gas sensors are the key equipment in transformer fault online monitoring systems, and developing new and efficient gas sensing materials is an important prerequisite for breaking through existing monitoring performance. Herein, the first-principles density functional theory (DFT) is employed to study the adsorption and gas-sensing performance of two metal atomic clusters (Pt 3 and Rh 3) anchored on a WTe 2 monolayer (C-WTe 2) for four typical fault characteristic gases (CO, CO 2 , H 2 , and C 2 H 2). These results suggest that four gases can stably bind to C-WTe 2 and exist in the form of chemical adsorption due to the high adsorption energy. Also, Rh 3 -WTe 2 exhibits high selectivity and repeatability towards CO and CO 2 due to its strong response and fast recovery characteristics when used in resistive sensors; Pt 3 -WTe 2 can detect and distinguish the four types of gases due to the significant and differentiated changes in work function when used in work function sensors. Therefore, both Pt 3 -WTe 2 and Rh 3 -WTe 2 monolayers are promising gas-sensing materials for the dissolved gases detection in oil. This investigation sheds light on devices of designing metal atomic cluster anchored WTe 2 -based gas sensor for improved transformer fault monitoring performances. [Display omitted] [ABSTRACT FROM AUTHOR]

Atomic-scale in situ (S)TEM and quasi-in situ XPS, together with DFT theoretical computations, allow us to go beyond previous nano-resolved microscopy studies of industrial NiMo/γ-Al 2 O 3 HDS catalysts to clarify how fragment structures and MoS 2 nanocrystals may change as a function of sulfo-reductive conditions. [Display omitted] • Investigated the atomic-scale microstructures of NiMo/γ-Al 2 O 3 catalysts to elucidate the reasons for the high stability. • Addressed the atomic-scale fragment structures and determined their impact on MoS 2 nanocrystals during applications. • Proposed multiple growth mechanisms for MoS 2 by the powerful combination of in situ characterizations and DFT calculations. Despite the significant global interest in removing S heteroatoms from fossil fuels to meet ever-tougher S emission rules, the single metal atoms and metal atom clusters (henceforth referred to as "fragment structures") present in industrial hydrodesulfurization (HDS) catalysts are rarely addressed. Herein, atomic-scale and in situ techniques were used to address the above gap and shed light on the structural evolution of these catalysts during their applications. The morphologies of fresh and post-diesel-reaction catalysts were examined using aberration-corrected scanning transmission electron microscopy and X-ray absorption fine structure. For the post-diesel-reaction catalysts, the MoS 2 nanocrystals grew with greater Mo coordination and fewer S vacancies, and the fragment structures were gradually reduced. The impact of fragment structures on MoS 2 during catalyst application was tracked using in situ techniques, and multiple MoS 2 growth mechanisms were proposed based on experimental and theoretical (density functional theory) data. Given the high structural sensitivity of hydrotreatment reactions, this study provides important insights into the previously debated issues related to the structure–activity relationships of industrial HDS catalysts. [ABSTRACT FROM AUTHOR]

Germanium, gallium, nitrogen, and oxygen deposition on both GaN(0001) and GaN(000 1 ̄) surfaces were investigated. A multiscale simulation framework was implemented. The DFT simulations were employed to reveal the interactions among the species and GaN surface. Energy diffusion barriers were obtained by the Nudged Elastic Band approach. A Poisson–Nernst–Planck model was implemented to calculate the concentration of each atomic species near GaN surface. The kinetic and unimolecular collision gas theories were incorporated to determine adsorption rates. These outcomes were integrated into a nanoscale kinetic Monte Carlo model. This model allowed to generate data on the surface diffusion and clustering of adsorbed atoms on GaN surfaces. As a result, an enhanced understanding of the deposition and agglomeration mechanisms was achieved. In particular, of the roles played by germanium and oxygen. Due to the relatively high diffusion energy barriers, germanium atoms act as pins around to which gallium atoms tend to cluster. The results align with both experimental observations and existing simulation literature. To the best of our knowledge, no previous DFT simulation results on germanium deposition on GaN have been reported. [Display omitted] • DFT calculations show that the Ga-polar is the most stable GaN surface. • The kinetic Monte Carlo simulations indicate that Ga and Ge tend to agglomerate. • Formation of Ge and Ga islands depends upon physical parameters. • The continuum scale gives realistic ions concentration near the adsorption layer. • TThe framework sheds light on the interfaces formation for power electronic devices. [ABSTRACT FROM AUTHOR]