Properties Of Clusters Research Articles

СТРАТЕГІЇ УПРАВЛІННЯ ІНТЕГРАЦІЙНИМИ ВИРОБНИЧИМИ ЛАНЦЮГАМИ ЗА УМОВ ВПРОВАДЖЕННЯ ЦИФРОВИХ ІННОВАЦІЙ

The article analyzes the scientific development of the theory of networks and flows from the standpoint of using their methodological approaches to solve the problems of forming a strategy for managing the innovative potential of cluster associations and finding new ways of its practical implementation. Strategic directions of business clustering under the condition of its digitization should ensure legislative support, appropriate digital infrastructure, elimination of digital gaps compared to other sectors of the economy, creation of proper conditions for the use of network tools, digital security, availability of regulatory support for innovation and investment development of network structures. This approach made it possible to form a set of principles and a portfolio of technologies for the interaction of network and integration structures, as well as to develop a digital mode of socio-economic transformations of integration production networks as components of ensuring sustainable competitive advantages under the conditions of globalization challenges. Fundamental aspects include: creation of a digital environment in which interaction between participants takes place with the help of digital services; formation of a secure digital asset management system; moving from descriptive to predictive and then administrative analytics. Based on these principles, a set of methodological tools for strategic management of the potential of network associations was developed and the main stimulators of investment and innovation development of integration production chains were established; a scientific hypothesis was formed, according to which digital management of latent manifestations of positive cluster properties should become the basis for the sustainable development of business associations.

Star cluster formation and feedback in different environments of a Milky Way-like galaxy

ABSTRACT It remains unclear how galactic environment affects star formation and stellar cluster properties. This is difficult to address in Milky Way-mass galaxy simulations because of limited resolution and less accurate feedback compared to cloud-scale models. We carry out zoom-in simulations to re-simulate 100–$300 \,\rm {pc}$ regions of a Milky Way-like galaxy using smoothed particle hydrodynamics, including finer resolution ($0.4 \,\rm {M_{\odot }{}}$ per particle), cluster-sink particles, ray-traced photoionization from O stars, H2/CO chemistry, and interstellar medium heating/cooling. We select ∼$10^{6} \,\rm {M_{\odot }{}}$ cloud complexes from a galactic bar, inner spiral arm, outer arm, and inter-arm region (in order of galactocentric radius), retaining the original galactic potentials. The surface densities of star formation rate and neutral gas follow $\Sigma _\mathrm{SFR}\propto \Sigma _\mathrm{gas}^{1.3}$, with the bar lying higher up the relation than the other regions. However, the inter-arm region forms stars two to three times less efficiently than the arm models at the same Σgas. The bar produces the most massive cluster, the inner arm the second, and the inter-arm the third. Almost all clusters in the bar and inner arm are small (radii <5 pc), while 30–50 per cent of clusters in the outer arm and inter-arm have larger radii more like associations. Bar and inner arm clusters rotate at least twice as fast, on average, than clusters in the outer arm and inter-arm regions. The degree of spatial clustering also decreases from bar to inter-arm. Our results indicate that young massive clusters, potentially progenitors of globular clusters, may preferentially form near the bar/inner arm compared to outer arm/inter-arm regions.

Gaia colour-magnitude diagrams of young open clusters

Context. Automated analyses of Gaia astrometric data have led to the discovery of many new high-quality open cluster candidates. When a good determination of their parameters is available, these objects become excellent tools for investigating the properties of our Galaxy. Aims. We explore whether young open clusters can be readily identified from Gaia data alone by studying the properties of their Gaia colour-magnitude diagrams. We also want to compare the results of a traditional cluster analysis with those of automated methods. Methods. We selected three young open cluster candidates from the UBC catalogue, ranging from a well-populated object with a well-defined sequence to a poorly populated and poorly defined candidate. We obtained classification spectra for the brightest stars in each. We redetermined members based on EDR3 data and fitted isochrones to derive the age, distance, and reddening. Results. All three candidates are real clusters with ages below 100 Ma. UBC 103 is a moderately populous cluster, with an age around 70 Ma. At a distance of ∼3 kpc, it forms a binary cluster with nearby NGC 6683. UBC 114 is a relatively proximal (∼1.5 kpc) poorly populated cluster containing two early-B stars. UBC 587 is a dispersed and very young (≤10 Ma) cluster located at ∼3 kpc, behind the Cygnus X region, which may be a valuable tracer of the Orion arm. Conclusions. The OCfinder methodology for the identification of new open clusters is extremely effective, with even poor candidates resulting in interesting detections. The presence of an almost vertical photometric sequence in the Gaia colour-magnitude diagram is a safe way to identify young open clusters. Automated methods for the determination of cluster properties give approximate solutions, but these are still subject to difficulties. There is some evidence suggesting that artificial intelligence systems may systematically underestimate extinction, which may impact in the age determination.

Connecting the young pulsars in Milky Way globular clusters with white dwarf mergers and the M81 fast radio burst

ABSTRACT The detections of four apparently young radio pulsars in the Milky Way globular clusters are difficult to reconcile with standard neutron star formation scenarios associated with massive star evolution. Here, we discuss formation of these young pulsars through white dwarf mergers in dynamically old clusters that have undergone core collapse. Based on observed properties of magnetic white dwarfs, we argue neutron stars formed via white dwarf merger are born with spin periods of roughly $10{\!-\!}100\,$ ms and magnetic fields of roughly $10^{11}{\!-\!}10^{13}\,$ G. As these neutron stars spin down via magnetic dipole radiation, they naturally reproduce the four observed young pulsars in the Milky Way clusters. Rates inferred from N-body cluster simulations as well as the binarity, host cluster properties, and cluster offsets observed for these young pulsars hint further at a white dwarf merger origin. These young pulsars may be descendants of neutron stars capable of powering fast radio bursts analogous to the bursts observed recently in a globular cluster in M81.

The Tiered Radio Extragalactic Continuum (T-RECS) simulation II: H i emission and continuum-H i cross-correlation.

Abstract In this paper we extend the Tiered Radio Extragalactic Continuum Simulation (T-RECS) to include ${\rm H\, {\small I}}$ emission. The ${\rm H\, {\small I}}$ T-RECS model is based on the most recent ${\rm H\, {\small I}}$ mass function estimates, combined with prescriptions to convert ${\rm H\, {\small I}}$ mass to total integrated ${\rm H\, {\small I}}$ flux. It further models source size, morphology and kinematics, including rotational velocity and ${\rm H\, {\small I}}$ line width. The continuum T-RECS model is updated to improve the agreement with deeper number counts available at 150 MHz. The model for star-forming galaxies (SFGs) is also modified according to the most recent indications of a star formation rate (SFR)–radio luminosity relation, which depends primarily on stellar mass rather than redshift. We further introduce prescriptions to associate an ${\rm H\, {\small I}}$ mass to the T-RECS radio continuum SFG and Active Galactic Nuclei (AGN) populations. This gives us a way to meaningfully associate counterparts between ${\rm H\, {\small I}}$ and continuum catalogues, thus building ${\rm H\, {\small I}}$ × continuum simulated observations. Clustering properties of the sources in both ${\rm H\, {\small I}}$ and continuum are reproduced by associating the galaxies to dark matter haloes of a cosmological simulation. We deliver a set of mock catalogues, as well as the code to produce them, which can be used for simulating observations and predicting results from radio surveys with existing and forthcoming radio facilities, such as the Square Kilometre Array (SKA).

Initial sizes of star clusters: implications for cluster dissolution during galaxy evolution

ABSTRACT Massive star clusters are often used as tracers of galaxy formation and assembly. In order to do so, we must understand their properties at formation, and how those properties change with time, galactic environment, and galaxy assembly history. The two most important intrinsic properties that govern star cluster evolution are mass and radius. In this paper, we investigate 10 theoretically and observationally motivated initial size–mass relations for star clusters, and evolve populations of clusters through galaxy formation models. We compare our results to each other and to observations of cluster populations in M83, M31, and the Milky Way. We find that none of our size–mass relations agree with the observations after 6–10 Gyr of evolution. We can successfully reproduce the cluster mass functions with models that have a small range of initial radii, and which do not allow cluster radii to change with time. However, these models do not agree with our understanding of cluster evolution, which does involve radius evolution, and do not match the observed distributions of radii. We note that there is a region of parameter space where clusters are optimally protected from both tidal shocks and evaporation due to two-body relaxation. Clusters that are allowed to evolve into this parameter space will likely survive. An improved understanding of both mass and radius evolution of star clusters in realistic, time-varying galactic potentials is necessary to appropriately make the connection between present-day cluster properties and their use as tracers of galaxy formation and assembly.

Molecular dynamics simulation of frictional properties of Pt cluster on graphite under load

Structural lubricity, characterized by nearly frictionless behavior at solid incommensurate interfaces with weak interactions, holds significant technological importance. However, various factors can lead to the breakdown of structural lubricity, such as spontaneous reorientation to a commensurate state, applied load, edge effects, deformations, and wear. To overcome these challenges, clusters can be employed at interfaces. With their high Young’s modulus and stiffness, clusters can withstand high loads and tolerate elastic deformations. Therefore, Pt cluster, which inherently possess incommensurate contact with graphite surface, are expected to exhibit structural superlubric behavior, even under high loads, as long as they can sustain incommensurate contact. Our molecular dynamics (MD) simulations, however, have revealed that a Pt cluster on graphite can undergo metastable transitions from the incommensurate state to a commensurate state, resulting in subsequent stick-slip behavior. In the absence of any external load, the Pt cluster has demonstrated the ability to maintain incommensurate contact with almost zero friction force, primarily attributed to its weak interaction with graphite. However, the presence of an applied load force leads to the loss of the initial incommensurate contact between the Pt cluster and graphite, resulting in the emergence of high friction forces and the breakdown of structural lubricity with a similar stick-slip behavior to that observed in the comparative simulations conducted for the commensurate state. It becomes evident that the maintenance of incommensurate contact is crucial for achieving superlubric behavior in Pt cluster-graphite systems, while the presence of an applied load force can disrupt this behavior and lead to higher friction forces.

Geometries, Electronic Structures, and Energetic Parameters of the first-row transition metal doped aluminum clusters Al16M

A theoretical study of geometry, stability, electronic structure, and magnetic property of neutral Al16M clusters with M being a first-row 3d transition metal atom, including Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn, are investigated in this theoretical study using quantum chemical approaches. The neutral Al16M clusters favor three kind of structures based on pure Al17 framework, including two exohedral doped isomers and one endohedral doped structure. There is a competition between the endoheral and the exohedral structures of Al16M with M being Ni, Cu, and Zn. The thermodynamic stability of encapsulated structure Al16Ni is confirm by the calculated average binding energy and embedded energy values. DFT calculation, however, indicate that the transition metal doping reduces the ionization potential of the pure aluminum clusters. Based on NBO calculations, a comprehensive picture of magnetic behavior is shown for Al16M clusters. Remarkably, the magnetism of the encapsualated Ni dopant is quenched in Al16 cage. Moreover, NBO calculations found that the 50-electron shells are completely preserved in both clusters Al16Sc and Al­16Ti and the remaining unpaired electron(s) localize(s) mainly on 3d atomic orbitals of the transition metal dopant.

Synthesis, fluorescence properties and structural characterization of two heteronuclear Zn(II)-Pr(III) clusters with a chain-shaped ether Schiff base ligand

Two new Zn(II)-Pr(III) heteronuclear clusters were synthesized by interfacial diffusion, [ZnPr(L)(NO3)2(OAc)(CH3OH)]·CH3CN (1) and [Zn4Pr2L4(terephthalate)2]·(NO3)2 (2) (H2L = bis(3-methoxysalicylaldehyde-3-oxopene-1,5-diamine). They have been characterized by elemental analysis, UV-Vis and IR spectroscopy, and single-crystal X-ray diffraction. Structural analysis revealed that 1 has a heterodinuclear structure, with Zn(II) in the inner cavity generated by deprotonated ligands L2- and Pr(III) in the larger outer cavity. Cluster 2 is a heterohexanuclear structure, in which the Pr(III) bridges two [ZnL] to form a heterotrinuclear secondary unit [Zn2PrL2], and then two terephthalates connect two secondary units to form a heterohexanuclear cluster structure. The solid-state fluorescence properties of clusters and ligand show that there are not only slightly blue-shifted fluorescence peak of ligand, but also characteristic fluorescence peaks of Pr(III) ions in the two clusters: 615 nm (3P0→3H6) for 1, 609 nm (1D2→3H4) and 646 nm (3P0→3F2) for 2, respectively. In the two clusters, the difference of ion fluorescence peaks is attributed to the symmetry difference of coordination geometric environment of Pr(III).

On sparsity, power-law, and clustering properties of graphex processes

AbstractThis paper investigates properties of the class of graphs based on exchangeable point processes. We provide asymptotic expressions for the number of edges, number of nodes, and degree distributions, identifying four regimes: (i) a dense regime, (ii) a sparse, almost dense regime, (iii) a sparse regime with power-law behaviour, and (iv) an almost extremely sparse regime. We show that, under mild assumptions, both the global and local clustering coefficients converge to constants which may or may not be the same. We also derive a central limit theorem for subgraph counts and for the number of nodes. Finally, we propose a class of models within this framework where one can separately control the latent structure and the global sparsity/power-law properties of the graph.

Elucidating the Mystery of DNA-Templating Effects on a Silver Nanocluster.

This presentation considers the effects that DNA-templating has on the optical properties of a 16-atom silver cluster. To accomplish this, hybrid quantum mechanical and molecular mechanical simulations of a Ag16-DNA complex have been carried out and compared with pure time-dependent density functional theory calculations of two Ag16 clusters in vacuum. The presented results show that the templating DNA polymers both red-shift the one-photon absorption of the silver cluster and increase its intensity. This occurs through a change in cluster shape prompted by the structural constraints of the DNA ligands combined with silver-DNA interactions. The overall charge of the cluster also contributes to the observed optical response, as oxidation of the cluster results in a simultaneous blue-shift of the one-photon absorption and a decrease in intensity. Additionally, the changes in shape and environment also lead to a blue-shift and enhancement of the two-photon absorption.

Investigating the role of carbon doping on the structural and energetic properties of small aluminum clusters using quantum Monte Carlo.

In this study, we investigate the energetics of small aluminum clusters doped with a carbon atom using several computational methods, including diffusion quantum Monte Carlo, Hartree-Fock (HF), and density functional theory. We calculate the lowest energy structure, total ground-state energy, electron population distribution, binding energy, and dissociation energy as a function of the cluster size of the carbon-doped aluminum clusters compared with the undoped ones. The obtained results show that carbon doping enhances the stability of the clusters mainly due to the electrostatic and exchange interactions from the HF contribution gain. The calculations also indicate that the dissociation energy required to remove the doped carbon atom is much larger than that required to remove an aluminum atom from the doped clusters. In general, our results are consistent with available theoretical and experimental data.

How the dynamical properties of globular clusters impact their γ-ray and X-ray emission

ABSTRACT The X-ray and γ-ray emission of globular clusters (GCs) is attributed to their large fraction of compact binary systems, especially those with millisecond pulsars (MSPs). We analyse a population of 124 Galactic GCs to investigate how their dynamical properties affect the formation and evolution of compact binary systems and how this can be translated into the clusters’ observed X-ray and γ-ray emission. We use mainly Chandra X-ray Observatory and Fermi Large Area Telescope observations to achieve our goals and start by detecting 39 GCs in γ rays, seven of which are not listed in previous Fermi-LAT catalogs. Additionally, we find that the total number of X-ray sources within a GC and its γ-ray luminosity are linearly correlated with the stellar encounter rate, indicating that compact binary systems are mainly formed via close stellar encounters. We also find an unexpected rise in the number of X-ray sources for GCs with low rates of stellar encounters, suggesting that there is a dynamical threshold where the formation of X-ray sources is dominated by stellar encounters. Furthermore, we use the Heggie-Hills law to find that subsequent stellar encounters in these compact binaries will, on average, make the binaries even harder, with basically no possibility of binary ionization. Finally, we find that all GCs are point-like sources in γ rays, indicating that the MSPs are concentrated in the clusters’ cores, likely due to dynamical friction.

Unexpected Reactivity of Cationic-to-Cationic Thiolate Ligand-Exchange Reaction on Au25 Clusters.

Thiolate-protected molecular noble metal clusters have attracted significant attention due to their unique physicochemical properties, which make them applicable in diverse fields such as catalysis, sensing, and bioimaging. Ligand-exchange reactions are a crucial technique for synthesizing and functionalizing these clusters, as they allow for the introduction of new ligands onto the cluster surface, which can alter their properties. While numerous studies have investigated neutral-to-neutral, neutral-to-anionic, and neutral-to-cationic ligand-exchange reactions, the cationic-to-cationic ligand-exchange reaction has never been reported, making the study of such reactions intriguing. In this study, the cationic ligand-exchange reaction on Au25(4-PyET-CH3+)x(4-PyET)18-x (x ≈ 9) clusters, which contain both neutral and cationic ligands in nearly equivalent amounts, was investigated. Contrary to our expectation that the cationic-to-cationic ligand-exchange reaction would be suppressed due to Coulombic repulsion between the surface cationic ligands and incoming cationic ligands, the originally existing cationic ligand was selectively exchanged. The choice of counterions for cationic ligands played a crucial role in controlling the selectivity of ligand exchange. For instance, bulky and hydrophobic counterions such as PF6- can cause steric hindrance and reduce Coulombic repulsion, which promotes cationic-to-cationic ligand exchange. Conversely, counterions like Cl- can lead to neutral-to-cationic ligand exchange due to reduced steric hindrance and increased Coulombic repulsion between cationic ligands. These findings provide a novel method for tailoring the properties of molecular gold clusters through controlled ligand exchange without requiring the design of thiolate ligands with varying geometrical structures.

Aminodiphosphine substituted 2Fe2Se complex as new precursor to single and double butterfly Fe/Se models related to FeFe hydrogenase models

A convenient way to synthesize the aminediphosphine (PNP) substituted Fe/Se models with [Fe2(µ-Se2)(CO)4(μ-PNP)] as a new precursor was described. Firstly, treatment of [Fe2(µ-SeR)2(CO)6] (R = C6H5 and CH2C6H5) with (Ph2P)2NBui in refluxing xylene gave [Fe2(μ-SeR)2(CO)4(μ-Ph2P)2NBui] (R = C6H51 and CH2C6H52). Further debenzylation reaction was found in complex 2 after long-time heating, and precursor complex [Fe2(μ-Se2)(CO)4(μ-Ph2P)2NBui] (3) was isolated with satisfactory yield. GC–MS analysis showed that the reaction involved the formation of (C6H5CH2)2. Further, the “open” single butterfly complex 2 and “closed” butterfly complex [Fe2(µ-pdSe)(CO)4(μ-Ph2P)2NBui] (pdSe = Se(CH2)3Se) (4) were conveniently prepared via a new synthetic route involving the reaction of 3 with 2 equiv of Et3BHLi, followed by treatment of the resulting [Fe2(μ-SeLi)2(CO)4(μ-Ph2P)2NBui] with BzBr (Bz = CH2C6H5) and Br(CH2)3Br, respectively. On the other hand, to obtain a double butterfly complex [{Fe2(μ-SeEt)(CO)4(μ-Ph2P)2NBui}2(μ-Se2)] (5), the first Fe4Se4 carbonyl model containing two PNP substituents, successive reactions were performed, including treating precursor complex 3 with EtMgBr, protonation with CF3CO2H (TFA), and air-direct oxidation. All the complexes were well characterized by various spectral techniques and particularly by X-ray crystallography. Moreover, a comparison of the electrochemical and electrocatalytic properties of single and double clusters 4 and 5 is also presented.

Internal Kinematics and Structure of the Bulge Globular Cluster NGC 6569 ∗ ∗ Based on observations collected at the European Southern Observatory, Cerro Paranal (Chile), in the context of the ESO-VLT Multi-Instrument Kinematic Survey (MIKiS survey) under Large Programmes 106.21N5 (PI: Ferraro), 195.D-0750 (PI: Ferraro), 193.D-0232 (PI: Ferraro). This publication makes use of data products from the Two Micron All

In the context of a project aimed at characterizing the properties of star clusters in the Galactic bulge, here we present the determination of the internal kinematics and structure of the massive globular cluster NGC 6569. The kinematics has been studied by means of an unprecedented spectroscopic data set acquired in the context of the ESO-VLT Multi-Instrument Kinematic Survey of Galactic globular clusters, combining the observations from four different spectrographs. We measured the line-of-sight velocity of a sample of almost 1300 stars distributed between ∼0.″8 and 770″ from the cluster center. From a subsample of high-quality measures, we determined the velocity dispersion profile of the system over its entire radial extension (from ∼5″ to ∼200″ from the center), finding the characteristic behavior usually observed in globular clusters, with a constant inner plateau and a declining trend at larger radii. The projected density profile of the cluster has been obtained from resolved star counts, by combining high-resolution photometric data in the center, and the Gaia EDR3 catalog radially extended out to for a proper sampling of the Galactic field background. The two profiles are properly reproduced by the same King model, from which we estimated updated values of the central velocity dispersion, main structural parameters (such as the King concentration, the core, half mass, and tidal radii), total mass, and relaxation times. Our analysis also reveals a hint of ordered rotation in an intermediate region of the cluster (40″ < r < 90″, corresponding to 2r c < r < 4.5r c ), but additional data are required to properly assess this possibility.

Large-scale clustering of buried X-ray AGN: Trends in AGN obscuration and redshift evolution

Aims. In order to test active galactic nucleus (AGN) unification and evolutionary models, we measured the AGN clustering properties as a function of AGN obscuration defined in terms of hydrogen column density, NH. In addition to measuring the clustering of unobscured (NH &lt; 1022 cm−2) and moderately obscured (1022 ≤ NH &lt; 1023.5) AGNs, we also targeted highly obscured sources (NH ≥ 1023.5) up to redshifts of z = 3. Methods. We have compiled one of the largest samples of X-ray-selected AGNs from a total of eight deep XMM/Chandra and multiwavelength surveys. We measured the clustering as a function of both AGN obscuration and redshift using the projected two-point correlation function, wp(rp). We modeled the large-scale clustering signal, measured the AGN bias, b(z, NH), and interpreted it in terms of the typical AGN host dark matter halo, Mhalo(z, NH). Results. We find no significant dependence of AGN clustering on obscuration, suggesting similar typical masses of the hosting halos as a function of NH. This result matches expectations of AGN unification models, in which AGN obscuration depends mainly on the viewing angle of the obscuring torus. We measured, for the first time, the clustering of highly obscured AGNs and find that these objects reside in halos with typical mass log Mhalo = 12.98−0.22+0.17[h−1 M⊙] (12.28−0.19+0.13) at low z ∼ 0.7 (high z ∼ 1.8) redshifts. We find that irrespective of obscuration, an increase in AGN bias with redshift is slower than the expectation for a constant halo mass and instead follows the growth rate of halos, known as the passive evolution track. This implies that for those AGNs the clustering is mainly driven by the mass growth rate of the hosting halos and galaxies across cosmic time.

FINEX: A Fast Index for Exact &amp; Flexible Density-Based Clustering

Density-based clustering aims to find groups of similar objects (i.e., clusters) in a given dataset. Applications include, e.g., process mining and anomaly detection. It comes with two user parameters (ε, MinPts) that determine the clustering result, but are typically unknown in advance. Thus, users need to interactively test various settings until satisfying clusterings are found. However, existing solutions suffer from the following limitations: (a) Ineffective pruning of expensive neighborhood computations. (b) Approximate clustering, where objects are falsely labeled noise. (c) Restricted parameter tuning that is limited to ε whereas MinPts is constant, which reduces the explorable clusterings. (d) Inflexibility in terms of applicable data types and distance functions. We propose FINEX, a linear-space index that overcomes these limitations. Our index provides exact clusterings and can be queried with either of the two parameters. FINEX avoids neighborhood computations where possible and reduces the complexities of the remaining computations by leveraging fundamental properties of density-based clusters. Hence, our solution is efficient and flexible regarding data types and distance functions. Moreover, FINEX respects the original and straightforward notion of density-based clustering. In our experiments on 12 large real-world datasets from various domains, FINEX frequently outperforms state-of-the-art techniques for exact clustering by orders of magnitude.

A theoretical study of the first-row transition metal doped germanium clusters Ge14M

Geometry, stability, electronic structure, and magnetic properties of Ge14M clusters with M being a 3d transition metal atom, from Sc to Zn, were studied using density functional theory (DFT) calculations at B3PW91/6-311+G(d) level. The obtained results found that Ge14M clusters preferentially exist in its lowest possible spin state, except for M being Fe and Cr. The thermodynamic stability of the structures has been evaluated through the average binding and embedded energies. Ge14Ti and Ge14V clusters are considered to be the most stable in the Ge14M series (M = Sc - Zn) with the geometry of the C2 point group where M is located in the center of the Ge12 hexagonal prism along with two Ge-atoms capping on two Ge6 faces. In this series Ge14M clusters, only Ge14Fe cluster is stable at the high spin state, with a magnetic moment of 2mB.

First principles data-driven potentials for prediction of iron carbide clusters

Many have reported the use of quantum chemistry approaches for evaluating the catalytic properties of iron carbide clusters. Unfortunately, structural energy calculations are computationally expensive when using density functional theory. The computational cost is prohibitive for high-throughput simulations with large length and time scales. In this paper, we generate data from 177 k clusters and choose state-of-the-art machine learning models within physical chemistry to train the features of this data. The generated potential gives a very high prediction accuracy on the order of the structure stability and achieves better adaptability/tolerance to poor structures of clusters. In addition, we use the machine learning potential to assist in high-throughput data collection and the prediction of hydrogen adsorption sites on cluster surfaces. We achieve more stable adsorption locations of the hydrogen atom more rapidly compared with traditional quantum chemical calculations.