Binding Energy Of Atom Research Articles

Calculation of the moscovium ground‐state energy by quantum algorithms

AbstractWe investigate the possibility to calculate the ground‐state energy of the atomic systems on a quantum computer. For this purpose we evaluate the lowest binding energy of the moscovium atom with the use of the iterative phase estimation and variational quantum eigensolver (VQE). The calculations by the VQE are performed with a disentangled unitary coupled cluster ansatz and with various types of hardware‐efficient ansatze. The optimization is performed with the use of the Adam and quantum natural gradients procedures. The scalability of the ansatze and optimizers is tested by increasing the size of the basis set and the number of active electrons. The number of gates required for the iterative phase estimation and VQE is also estimated.

Role of electronic binding energy on the stability of B, C, N, and O in Fe

Using first-principles density functional theory (DFT), we separate the distortion energy (DE) on Fe due to the introduction of solute atoms like B, C, N, and O at different sites from the electronic binding energy (EBE) of a solute atom with Fe. Contrary to the belief that distortion energy alone dictates the preference of solute atoms for a site in bulk, we show that EBE dictates the preference of the O for the octahedral site in Fe, with DE being the highest at the site. The site preference for C and N in bulk Fe is dictated by both DE and EBE. However, DE alone dictates site preference for B. The DE of solute atoms cannot be predicted by calculated radius, which is highest for B and lowest for O. We find that O and B have similar distortion energy due to large charge transfer to the O atom from Fe.

Theoretical investigation of dinitrogen to ammonia by Fe single atoms anchored on B/N-doped graphyne catalysts

Forced by the pressure of energy and environment, the realization of nitrogen reduction to synthesize ammonia under mild conditions has become a hot topic of research. Here by means of first principle computations, we systematically researched Fe single atoms anchored on B/N-doped graphyne catalysts. It was found that the formation energies of B and N dopants were 1.1284 and − 0.2505 eV, the binding energies of Fe atom were − 6.0695, −3.1507 and − 6.2978 eV in Fe/GY, Fe/B-GY and Fe/N-GY, respectively, indicating facile experimental synthesis. As B atom introduced in graphyne, an unpaired p electron in a sp-hybridized C atom appeared due to sphybridized B and C atoms, and the adsorption of N2 molecule on Fe/B-GY was strongest for the d-p interaction, which was also verified by the evident electron transfer between single Fe atom and N2 molecular. In this catalyst system, Fe/B-GY showed higher catalytic ability with the minimum ΔG⁎N-NH of 0.41 eV, and the competitive HER was inhibited with ΔGH⁎ of −4.5272 eV. This work provides a new research idea for the design and construction of efficient single metal atoms embedded in a two-dimensional material substrate for the synthesis of ammonia under mild conditions.

Interaction of 1/2〈111〉 interstitial dislocation loop with hydrogen and helium in tungsten: molecular dynamics simulation

The interaction of hydrogen and helium atoms with 1/2 〈111〉 interstitial dislocation loop in tungsten is investigated by molecular dynamics simulation. The binding energies of hydrogen and helium atoms around dislocation loop are calculated by molecular statics method. The results show that the outer region of the loop is attractive to the two atoms and the inner region is repulsive. Notably, the maximum binding energies are located in the core region of the dislocation loop. We have also studied the influence factors of the interaction between the dislocation loop and two atoms: free volume, lattice distortion degree, the radius and shape of the dislocation loop. The results show that large free volume benefits the retention of hydrogen and helium atoms, especially for helium. The less lattice distortion caused by the impurity atom, the more favorable for the dislocation loop to trap it. In addition, the larger dislocation loop with higher defect concentration results in stronger capture ability for the hydrogen and helium atoms. The different dislocation loop shapes lead to different binding energy distribution patterns. And the hydrogen and helium atoms tend to occupy the groove region of the concave dislocation loop. Finally, we employ the nudged elastic band theory and dynamics method to investigate the diffusion pattern of the hydrogen atom in the dislocation loop and find that the hydrogen atom tends to migrate spirally around dislocation line. Based on the obtained results, a reasonable interpretation of the interaction behaviors between the dislocation loop with hydrogen and helium atoms are discussed, which can provide essential parameters for mesoscopic scale simulations.

The performance of Li-modified B-doped phagraphene as a reversible hydrogen storage material in near-environmental conditions

In recent years, various applications of two-dimensional carbon nanomaterial phagraphene, whose protocells contain 5, 6 and 7 carbon rings, have been investigated. In this paper, first-principles and Grand Canonical Monte Carlo (GCMC) simulation methods are used to study the hydrogen storage properties of primitive and B-doped lithium modified phagraphene. The DFT results show that the binding energy of lithium atoms in Li-phagraphene is 2.0 eV. After B doping, the binding energy was significantly increased to 2.8 eV, and the molecular weight ratio of hydrogen was 13.07 wt%. According to the calculation of GCMC, the hydrogen storage weight ratio could reach 6.36 wt% under the environmental conditions of 298 K and 1 bar. The calculated Van't Hoff equation shows that doping B is more conducive to hydrogen desorption at atmospheric pressure. These results indicate that Li-modified B-doped phagraphene is a candidate material for realizing reversible hydrogen storage in near-environmental conditions.

Calculations of the Binding-Energy Differences for Highly-Charged Ho and Dy Ions

The binding-energy differences for ^{{163}}{text{H}}{{{text{o}}}^{{q + }}} and ^{{163}}{text{D}}{{{text{y}}}^{{q + }}} ions with ionization degrees q = 38, 39, and 40 are calculated. The calculations are performed using the large-scale relativistic configuration-interaction and relativistic coupled-clusters methods. The contributions from quantum-electrodynamics, nuclear-recoil, and frequency-dependent Breit-interaction effects are taken into account. The final uncertainty does not exceed 1 eV. Combining the obtained results with the binding-energy difference for neutral atoms calculated in [I.M. Savelyev, M.Y. Kaygorodov, Y.S. Kozhedub, I.I. Tupitsyn, and V.M. Shabaev, Phys. Rev. A 105, 012806 (2022)], we get the secondary differences of the ion–atom binding energies. These values can be used to evaluate the amount of energy released in the electron capture process in ^{{163}}{text{Ho}} atom (the Q value), provided mass differences of highly charged ions ^{{163}}{text{H}}{{{text{o}}}^{{q + }}} and ^{{163}}{text{D}}{{{text{y}}}^{{q + }}} is known from experiment. The Q value is required by experiments on the determination of the absolute scale of the electron neutrino mass by studying the beta-decay process.

Diffusion of Magnesium in Czochralski Silicon

The diffusion of magnesium in monocrystalline dislocation‐free Czochralski silicon (Cz–Si) with an oxygen concentration of (3–4) × 1017 cm−3 is studied. Initial silicon wafers are doped with Mg by using the sandwich technique. The impurity diffusion profiles are investigated in n‐Si samples by the differential conductivity method. The diffusivity of electrically active magnesium in the temperature range of 1,100–1,250 °C is two to three orders of magnitude lower than the values observed at doping high‐purity silicon crystals grown by the float‐zone method (Fz–Si). The diffusion in Cz–Si is retarded through the trapping of diffusing Mg atoms by oxygen‐related traps. The observed high value of the activation energy of Mg diffusion in investigated samples (4.1 eV) is due—along with the migration energy of interstitial magnesium in the crystal lattice (1.83 eV) —to the significant binding energy of Mg atoms with traps (2.27 eV). A study of the temperature dependence of the Hall effect in bulk‐doped samples reveals two types of deep double donors: interstitial Mg atoms and MgO complexes.

Increasing the Efficiency of Silicon Solar Elements by Doping with Nickel

It is shown that in the near-surface region of the solar cells (SCs) the concentration of nickel atoms is higher than in the bulk by 2–3 orders of magnitude, therefore, the gettering rate in the near-surface region is higher. Optimal modes of gettering by nickel clusters (i.e., nickel diffusion – Т = 800–850 °С, additional thermal annealing – Т = 750–800 °С) and the structure of a silicon SC were experimentally determined, which makes it possible to increase the efficiency of silicon SCs by 25–30% relative to the control. The physical mechanisms of the influence of the processes of diffusion of impurity nickel atoms and additional thermal annealing on the state of nickel atoms in the near-surface region and the SCs base and, accordingly, on the parameters of the SC are revealed. Physical models of the structure of a cluster of nickel atoms in silicon and the process of fast diffusing impurities gettering by clusters of nickel atoms are created. The binding energy of fast dissusing impurities atoms with a nickel cluster is estimated to be ~ 1.39 eV. The calculation shows that doping with nickel can increase the lifetime of minority charge carriers by 2–4 times, and the collection coefficient by 1.4–2 times. The experiment showed an increase in the minority charge carriers lifetime up to 2 times and an increase in efficiency by 25–30%.

Hyperspherical Cluster Model for Bosons: Application to Sub-threshold Halo States in Helium Drops

To describe long-range behaviour of one particle removed from a few- or a many-body system, a hyperspherical cluster model has been developed. It has been applied to the ground and first excited states of helium drops with five, six, eight and ten atoms interacting via a two-body soft gaussian potential. Convergence of the hyperspherical cluster harmonics expansion is studied for binding energies, root-mean-squared radii and overlaps of the wave functions of two helium drops differing by one atom. It was shown that with increasing model space the functional form of such overlaps at large distances converges to the correct asymptotic behaviour. The asymptotic normalization coefficients that quantify the overlaps’ amplitudes in this region are calculated. It was also shown that in the first excited state one helium atom stays far apart from the rest forming a two-body molecule, or a halo. The probability of finding the halo atom in the classically-forbidden region of space depends on the definition of the latter and on the valence atom binding energy. The total norm of the overlap integrals, the spectroscopic factor, represents the number of partitions of a many-body state into a chosen state of the system with one particle removed. The spectroscopic factors have been calculated and their sum rules are discussed giving a further insight into the structure of helium drops.

Rational Construction of 2D/3D Co3O4/NH2‐MIL‐53(Al) Heterostructures to Facilitate Photocatalytic Hydrogen Evolution

Based on the principle of strengthening photogenerated carrier separation and interfacial charge transfer, the heterojunction structure is constructed to improve the performance of photocatalytic hydrogen evolution. For this reason, a 3D gear‐like NH2‐MIL‐53(Al) material is synthesized by the template‐free hydrothermal method, and then the 2D irregular loose flake material Co3O4 derived from metal–organic framework is loaded. The hydrogen evolution rate of the composite photocatalyst Co3O4/NH2‐MIL‐53 (Al) is much greater than that of two single catalysts after progressively improving the experimental conditions. First of all, this is attributed to the heterojunction structure formed by the appropriate arrangement of energy bands. Second, the rationality of the heterojunction structure is confirmed by the change of binding energy of atoms in in situ irradiation X‐ray photoelectron spectroscopy and the calculation results of density functional theory. Further testing of the materials’ photoelectrochemical properties reveals that the composite photocatalyst Co3O4/NH2‐MIL‐53 (Al) has improved light adsorption, a lower overpotential, and a smaller Tafel slope. These results show that the hybrid material Co3O4/NH2‐MIL‐53 (Al) improves the charge separation activity and hydrogen evolution reaction kinetics, thus enhancing the photocatalytic performance.

Shake-up and shake-off effects in neutrinoless double- β decay

We revisit the role of shake-up and shake-off effects in neutrinoless double-beta decay, following earlier work by Drukarev et al. We find in agreement with Drukarev et al. that the Q value of the decay is reduced by any atomic excitation in the final-state but not by the difference in atomic binding energy of the initial and final state atoms, as was recently suggested by Mei and Wei. We discuss how the absorption of subsequent atomic de-excitation ejecta shifts the neutrinoless double-beta decay peak back to its nominal value. We propose an in situ experimental verification of these ideas, and discuss the impact of shake-up and shake-off on two-neutrino double-beta decay spectral shapes.

Analysis of Metal Clusters Based on Graph-Theoretic Interpretation of the Lowest Occupied Molecular Orbital

Molecules can be regarded as a kind of graph with atoms as vertices and bonds as edges. Therefore, it is possible to discuss the physical properties and reactivity of various molecules by applying the ideas of graph theory and network theory. Such research has flourished in the field of chemical graph theory. In this manuscript, it is shown that the lowest occupied molecular orbital (LOMO) can be interpreted graph theoretically as eigenvector centrality. This is one measure of centrality that characterizes the importance or influence of a node on a network. As such, LOMO coefficient can be regarded as a manifestation of centrality in an aggregate of atoms, indicating which atom plays the most important role in that aggregate or has the greatest influence on the atom network. Using such properties of LOMO, an analysis of the network of metal atoms in metal clusters is performed. The predictability of the binding energies of the constituent atoms of the metal clusters using LOMO coefficients is discussed.

DFT-Based Study for the Enhancement of CO2 Adsorption on Metal-Doped Nitrogen-Enriched Polytriazines.

Nitrogen-enriched polytriazine (NPT), a carbon nitride-based material, has received much attention for CO2 storage applications. However, to enhance the CO2 uptake capacity more efficiently, it is necessary to understand the interaction mechanism between CO2 molecules and NPT through appropriate modification of the structures. Here, we introduce a method to enhance the CO2 adsorption capacity of NPT by incorporating metal atoms such as Sn, Co, and Ni into the polytriazine network. DFT calculations were used to investigate the CO2 adsorption mechanism of the polytriazine frameworks by tracking the interactions between CO2 and the various interaction sites of NPT. By optimizing the geometry of the pure and metal-containing NPT frameworks, we calculated the binding energy of metal atoms in the NPT framework, the adsorption energy of CO2 molecules, and the charge transfer between CO2 molecules and the corresponding adsorption systems. In this work, we demonstrate that the CO2 adsorption capacity of NPT can be greatly enhanced by doping transition-metal atoms into the cavities of NPT.

Features of the Catalytic Cracking of Propane with a Step-Wise Change PrxYb2−xZr2O7

In this paper, the features of catalytic cracking of propane with a step-wise change in the composition of the catalyst from Pr2Zr2O7 to Yb2Zr2O7 were considered. For the research, samples of catalysts Pr2Zr2O7, (Pr0.75Yb0.25)2Zr2O7, (Pr0.5Yb0.5)2Zr2O7, (Pr0.25Yb0.75)2Zr2O7 and Yb2Zr2O7 were synthesized and analyzed. Analysis of the results from catalytic experiments showed that for the catalyst (Pr0.25Yb0.75)2Zr2O7, at a temperature of 700 °C, the conversion of propane reaches values of 100%, but for Yb2Zr2O7, this indicator decreases to 84%. The selectivity for ethylene is consistently reduced from 85% to 28% in several catalysts (Pr0.75Yb0.25)2Zr2O7 > Pr2Zr2O7 > (Pr0.5Yb0.5)2Zr2O7 >(Pr0.25Yb0.75)2Zr2O7 > Yb2Zr2O7. An increase in the number of surface adsorption centers leads to a predominant rupture of the C–C bond in the propane molecule with the formation of ethylene. When ytterbium ions are introduced into the catalyst, the amount of ethylene in the reaction products decreases, but the selectivity for propylene increases in the series Pr2Zr2O7 < (Pr0.75Yb0.25)2Zr2O7 < (Pr0.5Yb0.5)2Zr2O7 < Yb2Zr2O7 < (Pr0.25Yb0.75)2Zr2O7, which is associated with a decrease in the binding energy of carbon atoms in propane with the catalytic center during adsorption.

The decay Q value of neutrinoless double beta decay revisited

An earlier publication “The implication of the atomic effects in neutrinoless double beta (0νββ) decay” written by Mei and Wei has motivated us to compare the decay Q value (Qββ) derived from the decay of the parent nucleus to the daughter nucleus with the two ejected beta particles in the final state to the Qββ directly derived from the decay of the initial neutral atom to the final state of double-ionized daughter ion with the two ejected beta particles in the final state. We show that the results are the same, which is the mass-energy difference (ΔMc2) subtracted by the total difference of the atomic electron binding energy (ΔEb) between the ground states of initial and final neutral atoms. We demonstrate that ΔMc2 is the sum of Qββ and the atomic relaxation energy (ΔEb) of the atomic structure after the decay. Depending on the atomic relaxation time, the release of the atomic binding energy may not come together with the energy deposition of the two ejected beta particles.

On the origins of spontaneous spherical symmetry-breaking in open-shell atoms through polymer self-consistent field theory.

An alternative approach to density functional theory based on self-consistent field theory for ring polymers is applied to neutral atoms hydrogen to neon in their ground-states. The spontaneous emergence of an atomic shell structure and spherical symmetry-breaking of the total electron density are predicted by the model using the ideas of polymer excluded-volume between pairs of electrons to enforce the Pauli-exclusion principle and an exact electron self-interaction correction. The Pauli potential is approximated by neglecting inter-atomic correlations along with other types of correlations, and comparisons to Hartree-Fock theory are made, which also ignores correlations. The model shows excellent agreement with Hartree-Fock theory to within the standards of orbital-free density functional theory for the atomic binding energies and density profiles of the first six elements, providing exact matches for the elements hydrogen and helium. The predicted shell structure starts to deviate significantly past the element neon, and spherical symmetry-breaking is first predicted to occur at carbon instead of boron. The self-consistent field theory energy functional that describes the model is decomposed into thermodynamic components to trace the origin of spherical symmetry-breaking. It is found to arise from the electron density approaching closer to the nucleus in non-spherical distributions, which lowers the energy despite resulting in frustration between the quantum kinetic energy, electron-electron interaction, and the Pauli exclusion interaction. The symmetry-breaking effect is found to have a minimal impact on the binding energies, which suggests that the spherical-averaging approximation used in previous work is physically reasonable when investigating atomic systems. The pair density contour plots display behavior similar to polymer macro-phase separation, where individual electron pairs occupy single lobe structures that together form a dumbbell shape analogous to the 2p orbital shape. It is further shown that the predicted densities satisfy known constraints and produce the same total electronic density profile that is predicted by other formulations of quantum mechanics.

Coulomb-Zeeman-Stark problem in two dimensions

Coulomb-bound systems in reduced dimensions are sensitive probes of increased confinement. For example, the ground-state binding energy of hydrogen atoms increases by a factor of 4 when passing from three to two dimensions. Recently, quasi--two-dimensional hydrogen has been realized experimentally in the form of low-dimensional excitons. Their sensitivity to external electric and magnetic perturbations is reduced by the confinement. To quantify the reduction, we consider in the present work two-dimensional hydrogen in crossed electric and magnetic fields. We compare analytical, numerical, and variational results for the binding energy and dipole polarizability in arbitrary magnetic fields. Our analytical expressions for both weak and strong magnetic fields are supplemented by accurate variational and hypergeometric resummation results, thereby covering arbitrary magnetic fields.

Optimizing Heterointerface of Co2P–CoxOy Nanoparticles within a Porous Carbon Network for Deciphering Superior Water Splitting

It is of great significance to design a bifunctional electrocatalyst for promoting hydrogen (HER) and oxygen (OER) evolution reactions simultaneously. Herein, inspired by the appropriate H atom binding energy on cobalt phosphides and excellent oxygen evolution kinetics on cobalt oxides, the regulative synthesis of a Co2P–Co x O y (Co x O y = CoO or Co3O4) heterogeneous nanoparticle‐anchored porous carbon network electrocatalyst via one‐pot heat treatment is reported. The as‐synthesized Co2P–Co3O4/C exhibits superior electrochemical activity with low overpotentials of 86 mV for HER and 246 mV for OER at 10 mA cm−2 in an alkaline electrolyte. Moreover, compared to the commercial Pt/C || RuO2/C system, the Co2P–Co3O4/C || Co2P–Co3O4/C system presents outstanding activity toward overall water splitting (1.55 V@10 mA cm−2), which is well maintained over long‐term (120 h) electrocatalysis. Density functional theory calculations show that the rich interfaces between Co2P and Co3O4 offer a synergistic effect, which enables Co2P–Co3O4/C as an excellent electrocatalyst toward both HER and OER.

Rare-earth metal-N6 centers in porous carbon for electrocatalytic CO2 reduction.

Single-atom catalysts fabricated using rare earth elements have emerged for electrocatalytic carbon dioxide reduction, but they need to be studied systematically and intensively. Herein, density functional theory was employed to determine the electrocatalytic CO2 reduction activity of rare earth-N6 porous carbon (Re = Ce, Nd, Sm, Eu, Gd, Tb, Er, Tm, Yb, and Lu) single-atom catalysts. The results revealed that the binding energy of the rare-earth atoms to the N6C monolayers in the ten studied Re-N6C monatomic catalysts is much more negative than the cohesion energy of the bulk rare-earth metal, which makes rare-earth atoms stably dispersed in the N6C skeleton. CO is the primary chemical product of electrocatalytic CO2 reduction by Ce, Eu, and Lu. The primary product of the six monatomic species, i.e., Nd, Sm, Tb, Er, Tm, and Yb, is HCOOH. The dominant product of Gd is CH4. The limiting potentials of these catalysts are in the range of 0.31-0.786 V and their overpotentials are in the range of 0.06-0.707 V, all of which are relatively low, showing that they are potential and promising electrocatalysts for CO2 reduction. Subsequently, Eu-N6C was experimentally synthesized and used for electrocatalytic CO2 reduction to obtain CO products, and the overpotential showed good agreement with the theoretically calculated values.

Synthesis of Non-centrosymmetric Dipolar 4,4'-Bipyridines: Potential Molecular Tectons for Programmed Assembly of Supramolecular Systems.

In this report, we describe a modular synthesis approach towards a new series of non-centrosymmetric, dipolar 4,4'-bipyridines bearing 2,6- and 3,5-functionalized pyridyl moieties at the peripheries. Central to our strategy is the selective substitution on only one pyridyl motif that could contain electron-donating (-CH3 ) or electron-withdrawing (-F, -Cl, -CF3 ) groups which causes electronic/steric effects on one nitrogen atom in 4,4'-bipyridines. This synthetic protocol was further applied to prepare azo-functionalized (-N=N-) asymmetric bipyridines and non-centrosymmetric 4,4'-bipyridine N-oxide scaffolds, which overcome the synthetic hurdles oxidizing 4,4'-bipyridines to N-monoxides selectively at only one pyridine. Compared to the conventional symmetrical bipyridines, the dipolar non-centrosymmetric molecular tectons pave the way for the realization of non-centrosymmetric supramolecular assemblies because of the difference in the binding energy of the pyridyl nitrogen atoms.