Binding Energies Of Orbitals Research Articles

Electron and Positron Impact Ionization of SF6−nHn(n = 0 − 6); {SCln, SFn−1Cl(n = 1 − 6)} and SF5X(X = CN, CFO)

We have calculated the electron and positron impact ionization of a set of molecules, SF6−nHn(n=0−6), SCln(n=1−6), SFn−1Cl(n=1−6) and SF5X(X=CN,CFO), for which there are much fewer data in the literature. We have optimized the targets, and their electric polarizability is calculated along with their orbital binding and kinetic energies within the Hartree–Fock approximation that serve as input to the Binary Encounter Bethe (BEB) model for both electron and positron ionization. Most of the targets are investigated for the first time, apart from SF6, for which we compared our data with various experimental and theoretical data, giving us a good comparison.

On the pollution of white dwarfs by exo-Oort cloud comets

ABSTRACT A large fraction of white dwarfs (WDs) have metal-polluted atmospheres, which are produced by accreting material from remnant planetary systems. The composition of the accreted debris broadly resembles that of rocky Solar system objects. Volatile-enriched debris with compositions similar to long-period comets (LPCs) is rarely observed. We attempt to reconcile this dearth of volatiles with the premise that exo-Oort clouds (XOCs) occur around a large fraction of planet-hosting stars. We estimate the comet accretion rate from an XOC analytically, adapting the ‘loss cone’ theory of LPC delivery in the Solar system. We investigate the dynamical evolution of an XOC during late stellar evolution. Using numerical simulations, we show that 1–30 per cent of XOC objects remain bound after anisotropic stellar mass-loss imparting a WD natal kick of ${\sim}1 \, {\rm km \, s^{-1}}$. We also characterize the surviving comets’ distribution function. Surviving planets orbiting a WD can prevent the accretion of XOC comets by the star. A planet’s ‘dynamical barrier’ is effective at preventing comet accretion if the energy kick imparted by the planet exceeds the comet’s orbital binding energy. By modifying the loss cone theory, we calculate the amount by which a planet reduces the WD’s accretion rate. We suggest that the scarcity of volatile-enriched debris in polluted WDs is caused by an unseen population of 10–$100 \, \mathrm{au}$ scale giant planets acting as barriers to incoming LPCs. Finally, we constrain the amount of volatiles delivered to a planet in the habitable zone of an old, cool WD.

Charge transfer and electronic relaxation effects in the photoemission of EMIM-DCA ionic liquid vapor

Ultraviolet photoelectron spectroscopy (UPS) measurements of EMIM-DCA vapors have been conducted. Density functional theory (DFT), Møller–Plesset perturbation theory (MP2) and many-body perturbation theory calculations (GW) have been used to interpret the experimentally measured spectra. The vapor of ionic liquids normally consists of isolated ion-pairs and the corresponding photoemission spectra should reflect the electronic binding energies of the molecular orbitals. The UPS spectra have revealed that many photolines are shifted when compared to ab initio calculation results. The hybrid DFT functionals, which performed very good in the description of the UPS spectra of many other ionic liquid vapors have shortcomings in the EMIM-DCA case. The MP2 calculation and the quasiparticle GW approach are shown to offer a better description of the experimental UPS spectra. The charge distribution analysis showed that there seems to be a favorable charge transfer from the cation to the anion upon ionization. The new data provides strong support to the argument that in some cases DFT still has difficulties in the modeling of IL ion-pairs.

Cu2In alloy-embedded ZrO2 catalysts for efficient CO2 hydrogenation to methanol: promotion of plasma modification.

Cu1In2Zr4-O-C catalysts with Cu2In alloy structure were prepared by using the sol-gel method. Cu1In2Zr4-O-PC and Cu1In2Zr4-O-CP catalysts were obtained from plasma-modified Cu1In2Zr4-O-C before and after calcination, respectively. Under the conditions of reaction temperature 270°C, reaction pressure 2MPa, CO2/H2 = 1/3, and GHSV = 12,000mL/(g h), Cu1In2Zr4-O-PC catalyst has a high CO2 conversion of 13.3%, methanol selectivity of 74.3%, and CH3OH space-time yield of 3.26mmol/gcat/h. The characterization results of X-ray diffraction (XRD), scanning electron microscopy (SEM), and temperature-programmed reduction chemisorption (H2-TPR) showed that the plasma-modified catalyst had a low crystallinity, small particle size, good dispersion, and excellent reduction performance, leading to a better activity and selectivity. Through plasma modification, the strong interaction between Cu and In in Cu1In2Zr4-O-CP catalyst, the shift of Cu 2p orbital binding energy to a lower position, and the decrease in reduction temperature all indicate that the reduction ability of Cu1In2Zr4-O-CP catalyst is enhanced, and the CO2 hydrogenation activity is improved.

Montmorillonite-mediated electron distribution of zirconium phosphate for accelerating remediation of cadmium-contaminated water and soil

Rapid and efficient remediation of heavy metal-contaminated water and soil bodies has been a hot topic in ecological remediation. However, designing and synthesizing green remediation materials with fast kinetics and high adsorption capacity is still challenging. In this study, a novel heavy metal remediation material (Mt@ZrP) has been prepared using montmorillonite to induce the structural rearrangement of zirconium phosphate (ZrP). The results showed that montmorillonite could mediate the external electron distribution of ZrP, thus increasing its O 1 s binding energy. Distinct from the electrostatic adsorption of bare ZrP, Mt.@ZrP with higher orbital binding energy led to an extra adsorption mode with internal spherical coordination. Such characteristics dramatically shortened the adsorption equilibrium time (23 min) and enhanced the adsorption capacity (275.6 mg/g-ZrP) of Mt.@ZrP for Cd removal in comparison to those of bare ZrP (220 min, 196.1 mg/g-ZrP). As for soil remediation, Mt.@ZrP presented a faster Cd removal rate than bare ZrP. The residual fraction increased from 22.03% (control) to 28.47% (Mt@ZrP, 1 wt%) and 37.54% (Mt@ZrP, 3 wt%), which significantly decreased the biological efficacy of Cd in the soil. These findings could provide a novel strategy for the design and synthesis of excellent remediation materials for the rapid and efficient removal of heavy metals in water and soil.

Partial Ionization Cross Sections of Tungsten Hexafluoride Due to Electron Impact

The ionization data of a neutral molecule are crucial to model the energy deposition and dissociative ionization process. We study theoretically the electron impact ionization process and report on the dissociative ionization cross sections of the tungsten hexafluoride cations invoking the modified-binary-encounter-Bethe model. In this model, the binary-encounter-Bethe model is modified by applying the transformation to the binding energies of the molecular orbitals and then normalizing the partial ionization cross sections of the cations using the branching ratios. The normalization is performed at a particular energy and ensures that the branching ratios of different fragments are summed to unity. The model yielded satisfactory results for both the singly and doubly ionized ions. The approach validates the results of Basner et al. The advantages and limitations of this model are also discussed. This work corroborates the importance of mass spectrometry data in the proper understanding of the ionization process.

Ultrathin two-dimensional nanosheet metal-organic frameworks with high-density ligand active sites for advanced lithium-ion capacitors

Two-dimensional (2D) metal-organic frameworks (MOFs) exhibit great promise as high-energy anode materials for next-generation lithium-ion capacitors (LICs) due to their tunable chemistry and short ion transport paths. Nevertheless, high-throughput production of ultrathin 2D MOFs and energy storage mechanism analysis are still full of challenges. Here, theoretical calculations indicate that partial introduction of Fe in Co sites can enhance interaction of metal centers with water in solvents due to the strong 3d-2p orbital binding energy, which induces ultrathin nanosheets, resulting in exposure of high-density ligand active sites, lower band gap and higher Young modulus during lithium insertion. Greatly, ultrathin 2D Co/Fe-BDC nanosheets are obtained with a bottom-up method and can be scaled up to high-throughput production. In/ex-situ results further reveal highly reversible insertion/extraction reactions accompanied by crystalline to amorphous for Co/Fe-BDC anodes. LICs with optimal Co4Fe-BDC anode deliver high energy density (199.7 Wh kg−1) and power density (10,000 W kg−1), together with superior cycle lifespan. This work offers in-depth insights for the high-throughput synthesis and the storage mechanism in 2D MOFs.

Basis Set Selection for Molecular Core-Level GW Calculations.

The GW approximation has been recently gaining popularity among the methods for simulating molecular core-level X-ray photoemission spectra. Traditionally, Gaussian-type orbital GW core-level binding energies have been computed using either the cc-pVnZ or def2-nZVP basis set families, extrapolating the obtained results to the complete basis set limit, followed by an element-specific relativistic correction. Despite achieving rather good accuracy, it has been previously stated that these binding energies are chronically underestimated. In the present work, we show that those previous studies obtained results that were not well-converged with respect to the basis set size and that, once basis set convergence is achieved, there seems to be no such underestimation. Standard techniques known to offer a good cost-accuracy ratio in other theories demonstrate that the cc-pVnZ and def2-nZVP families exhibit contraction errors and might lead to unreliable complete basis set extrapolations for absolute binding energies, often deviating about 200-500 meV from the putative basis set limit found in this work. On the other hand, uncontracted versions of these basis sets offer vastly improved convergence. Even faster convergence can be obtained using core-rich property-optimized basis set families like pcSseg-n, pcJ-n, and ccX-nZ. Finally, we also show that the improvement observed for core properties using these specialized basis sets does not degrade their description of valence excitations: vertical ionization potentials and electron affinities computed with these basis sets converge as fast as the ones obtained with the aug-cc-pVnZ family, thus offering a balanced description of both core and valence regions.

Inspiraling corrugation-induced quantum effects on neutron star binary plane

We use the path-integral formula and investigate some dynamical quantum effects induced by the inspiraling lateral corrugation of orbital plane in gravitationally bound neutron star (NS) binaries, with orbital separation of 109 m. Based on Dewitt's approach, we calculate the gravitational Casimir energy cost of the binary plane, which consists of statically gravitational effects and deformation-induced effects. It is found that the static effects include a term coming from the self-gravity of the orbital plane and the contribution of Newtonian gravitational potential of the binary system. While the deformation-induced effect also results from two parts, i.e. the instability of orbital binding energy, scaling as 1(R−r)2, and the dynamically Casimir energy cost of the orbital binding energy, decaying as 1(R−r)4. The dynamically gravitational Casimir phenomena and the corresponding energy cost modify the spiral-in orbital motion of the binary and thus the frequency of released gravitational waves (GWs). We consider the mechanical response of two NS components and qualitatively study the corrections to the orbital motion of the system and the GW frequencies. It is found that the dynamical Casimir effects exert a dissipative force on the binary plane, depending on the frequency of GWs. The resultant dissipation may enhance with the decaying separation and increasing GW frequencies, which subsequently accelerates the orbital decay of the binary. However, the dissipation rate just has an order of 10−70 eV/s. So the corrections to the dynamics of NS binaries are very marginal, by considering the wide separation, the cosmological coalescence time, and low-frequency GWs of the system.

Ionization energy and valence electron orbital binding energy of superheavy element Og(<i>Z</i> = 118) and its homologs

The ionization energy of the superheavy element Og (<i>Z</i> = 118) and its homolog elements Ar, Kr, Xe, Rn, and their ions are systematically calculated by using the GRASP2K program based on the multi-configuration Dirac-Hartree-Fock (MCDHF) method, taking into account relativistic effects, electron correlation effects between valence shell electrons, quantum electrodynamics effects, and Breit interaction. To reduce the uncertainty of the ionization energy derived from electron correlation effects which are not fully considered, the ionization potential of the superheavy element Og<sup>0–2+</sup> and its homolog element Rn<sup>0–2+</sup> are extrapolated by the extrapolation method. The ionization energy of extrapolated Rn<sup>0–5+</sup> and Og<sup>5+</sup> coincide well with experimental and other theoretical values. These results can be used to predict the unknown physical and chemical properties of the atoms and compounds of the superheavy element Og. In addition, the calculation results of the electron orbital binding energy of the atomic valence shell of the superheavy element Og and its homolog elements Ar, Kr, Xe, and Rn under relativistic and non-relativistic conditions show that owing to the relativistic effect, there occur strong orbital contraction phenomena in the 7s orbital and 7p<sub>1/2</sub> orbital and strong splitting phenomena in the 7p<sub>1/2 </sub> orbital and 7p<sub>3/2</sub> orbital of Og, which may cause the physical and chemical properties of the superheavy element Og to differ from those of other homologs.

Ionization energy and valence electron orbital binding energy of the superheavy element Og(Z=118) and its homologs

The ionization energy of the superheavy element Og (Z=118) and its homolog elements Ar, Kr, Xe, Rn, and their ions were systematically calculated using the GRASP2K program based on the multi-configuration Dirac-Hartree-Fock (MCDHF) method, taking into account relativistic effects, electron correlation effects between valence shell electrons (VV), quantum electrodynamics (QED) effects, and Breit interaction. To reduce the uncertainty of the ionization energy derived from electron correlation effects which are not fully considered, the ionization potential of the superheavy element Og<sup>0-2+</sup> and its homolog element Rn<sup>0-2+</sup> are extrapolated by the extrapolation method. The ionization energy of extrapolated Rn<sup>0-5+</sup> and Og<sup>5+</sup> coincides well with experimental and other theoretical values. These results can be used to predict the unknown physical and chemical properties of the atoms and compounds of the superheavy element Og. In addition, the calculation of the electron orbital binding energy of the atomic valence shell of the superheavy element Og and its homolog elements Ar, Kr, Xe, and Rn under relativistic and non-relativistic conditions shows that due to the relativistic effect, there is a strong orbital contraction phenomenon in the 7s and 7p<sub>1/2</sub> orbitals and a strong splitting phenomenon occurs in the 7p<sub>1/2</sub>and 7p<sub>3/2</sub> orbitals of Og, which may cause the physical and chemical properties of the superheavy element Og to be different from other homologs.

Spin-orbit effects for compact binaries in scalar-tensor gravity

Gravitational waves provide us with a new window into our Universe, and have already been used to place strong constrains on the existence of light scalar fields, which are a common feature in many alternative theories of gravity. However, spin effects are still relatively unexplored in this context. In this work, we construct an effective point-particle action for a generic spinning body that can couple both conformally and disformally to a real scalar field, and we show that requiring the existence of a self-consistent solution automatically implies that if a scalar couples to the mass of a body, then it must also couple to its spin. We then use well-established effective field theory techniques to conduct a comprehensive study of spin-orbit effects in binary systems to leading order in the post-Newtonian (PN) expansion. Focusing on quasicircular nonprecessing binaries for simplicity, we systematically compute all key quantities, including the conservative potential, the orbital binding energy, the radiated power, and the gravitational-wave phase. We show that depending on how strongly each member of the binary couples to the scalar, the spin-orbit effects that are due to a conformal coupling first enter into the phase at either 0.5 PN or 1.5 PN order, while those that arise from a disformal coupling start at either 3.5 PN or 4.5 PN order. This suppression by additional PN orders notwithstanding, we find that the disformal spin-orbit terms can actually dominate over their conformal counterparts due to an enhancement by a large prefactor. Accordingly, our results suggest that upcoming gravitational-wave detectors could be sensitive to disformal spin-orbit effects in double neutron star binaries if at least one of the two bodies is sufficiently scalarised.

A novel porous polyimide membrane with ultrahigh chemical stability for application in vanadium redox flow battery

The chemical stability of membranes is critical for the application in vanadium redox flow battery (VRFB). In this work, a novel porous cross-linked polyimide membrane (PCrPI) with ultrahigh chemical stability is prepared by using β-cyclodextrin (β-CD) as a template. The unique cross-linking structure and imidazole group with Donnan effect of PCrPI membrane can effectively hinder the migration of vanadium ions. Meanwhile, the imidazole group and porous structure of the PCrPI membrane can also enhance ionic transfer and reduce area resistance. In VRFB tests, the PCrPI membrane exhibits higher coulomb efficiency (CE: 96.3–99.6%) and energy efficiency (EE: 67.9–88.9%) than commercial Nafion 212 membrane (CE: 74.3–94.8%; EE: 67.7–77.5%) at the current density of 40–200 mA cm−2. In addition, the charge–discharge cycles of VRFB with the PCrPI membrane are performed 2250 times, and the running time of PCrPI-10 membrane is among the top level compared with previously reported membranes. Meanwhile, the excellent durability of PCrPI-10 membrane is also explained through theoretical calculation with natural bond orbital charge and binding energy. The results show that the application of PCrPI-10 membrane in VRFB will embrace a bright future.

Angular distribution and energy spectra of photoelectrons from tetrahydrofuran illuminated by VUV photon source

Photoelectron emission from the valence shell of biologically relevant tetrahydrofuran (THF) molecule is studied. Energy and angular distributions of photoelectrons from THF ionized by a He(I) vacuum ultraviolet (VUV) photon source are measured. Theoretical calculations performed for the binding energies of orbitals and photoelectron intensities are in reasonable agreement with measurement. The observed angular distributions show the determining role of dipole transition mechanism.

Lanthanum group: Detection and correction of errors in orbital binding energy measurements of internal shells

Experimental data on electronic binding energies in a ground state of lanthanides are analyzed. Internal individual shells K, L, M, N are studied in detail. The data scatter is discussed. Atomic number similarity law of orbital binding energies is shown and deviations from it in some experimental results are treated as measurement errors. Polynomial interpolation of patterns makes it possible to restore missing and correct erroneous data. Comparison is made with experimental data from other sources and theoretical results.

Investigation of chemical bonding and electronic network of rGO/PANI/PVA electrospun nanofiber

Reduced graphene oxide-reinforced polyaniline and poly(vinyl alcohol) (PVA/PANI/rGO) nanofibers were synthesized by electrospinning method with different rGO content varying from 1 to 5wt%. The PVA/PANI/rGO nanofibers were characterized by SEM, FTIR, Raman, XPS and UV–visible spectroscopy to investigate the morphology, vibrational bonding, elemental composition and optical properties, respectively. The XRD results reveal the broad peak at 2θ = 25° corresponding to (002) for rGO and three peaks at 2θ = 14°, 20° and 25° corresponding to (011), (020) and (200), respectively for PANI. The FTIR signatures at 1088, 1245, 1359, 1411, 1717, 2930 and 3305 cm−1 correspond to ν-(C–O), ν-(N–H), ν-(C–OH), ν-(C=O), ν-(C–H) and ν-(O–H), respectively. The optical bandgap of PVA/PANI/rGO nanofibers was decreased from 4.20 to 4.07 eV as the rGO wt% increased. The structural and electronic network of carbon was analyzed by semiempirical Gaussian peaks to predict various binding energy of core orbital binding energy spectra in PVA/PANI/rGO nanofibers.

In Silico Modeling of New "Y-Series"-Based Near-Infrared Sensitive Non-Fullerene Acceptors for Efficient Organic Solar Cells.

This work was inspired by a previous report [Janjua, M. R. S. A. Inorg. Chem. 2012, 51, 11306–11314] in which the optoelectronic properties were improved with an acceptor bearing heteroaromatic rings. Herein, we have designed four novel Y-series non-fullerene acceptors (NFAs) by end-capped acceptor modifications of a recently synthesized 15% efficient Y21 molecule for better optoelectronic properties and their potential use in solar cell applications. Density functional theory (DFT) along with time-dependent density functional theory (TDDFT) at the B3LYP/6-31G(d,p) level of theory is used to calculate the band gap, exciton binding energy along with transition density matrix (TDM) analysis, reorganizational energy of electrons and holes, and absorption maxima and open-circuit voltage of investigated molecules. In addition, the PM6:YA1 complex is also studied to understand the charge shifting from the donor polymer PM6 to the NFA blend. Results of all parameters suggest that the DA’D electron-deficient core and effective end-capped acceptors in YA1–YA4 molecules form a perfect combination for effective tuning of optoelectronic properties by lowering frontier molecular orbital (FMO) energy levels, reorganization energy, and binding energy and increasing the absorption maximum and open-circuit voltage values in selected molecules (YA1–YA4). The combination of extended conjugation and excellent electron-withdrawing capability of the end-capped acceptor moiety in YA1 makes YA1 an excellent organic solar cell (OSC) candidate owing to promising photovoltaic properties including the lowest energy gap (1.924 eV), smallest electron mobility (λe = 0.0073 eV) and hole mobility (λh = 0.0083 eV), highest λmax values (783.36 nm (in gas) and 715.20 nm (in chloroform) with lowest transition energy values (Ex) of 1.58 and 1.73 eV, respectively), and fine open-circuit voltage (Voc = 1.17 V) with respect to HOMOPM6–LUMOacceptor. Moreover, selected molecules are observed to have better photovoltaic properties than Y21, thus paving the way for experimentalists to look for future developments of Y-series-based highly efficient solar cells.

Binding Energies in Electron Shells of Rare-Earth Atoms

Experimental data on the orbital binding energies in each of electron subshells of rare-earth elements from lanthanum to lutetium including the first ionization potentials have been analyzed in detail using a semiclassical method to separate the dependences of binding energies on the atomic number and quantum numbers. The spread of experimental data for the N and O shells of lanthanides has been discussed. The analysis has confirmed the law of similarity of orbital binding energies in the atomic number in individual subshells that differs from Moseley’s law. Deviation from the common dependence usually indicates the inaccuracy of the corresponding measurement. The simplest interpolation of the found relations makes it possible to approximate experimental data with an accuracy of about 1%, to reconstruct missed data, and to correct inaccurate measurement results. The analysis of theoretical results also reveals such relations and their violation is attributed to the violation of the order of filling of 4f states.

Designing of benzothiazole based non-fullerene acceptor (NFA) molecules for highly efficient organic solar cells

To enhance the efficiency of organic solar cells (OSCs), five non-fullerene π-conjugated acceptor molecules namely BTM1, BTM2, BTM3, BTM4 and BTM5 are designed from recently reported 16.5% efficient acceptor molecule BTP-Cl. The molecules in the present quantum chemical investigation consist of benzothiazole (BT) core with different chemical species on the terminal side. The optoelectronic study of BTM1-BTM5 reveals that BTM3 and BTM4 molecules are superior with respect to absorption range found at the wavelengths of 780 and 791 nm as compared to 746 nm of reference molecule BTP-Cl. Frontier molecular orbital (FMO) and transition density matrix (TDM) analysis are performed that give basic information about the distribution of charges among investigated molecules. All investigated molecules exhibit charge density spread over the entire molecules. The BTM4 and BTM5 molecules efficiently transfer their electron densities from highest occupied molecular orbital (HOMO) to lowest unoccupied molecular orbital (LUMO) with narrow bandgaps of 1.86 eV and 2.14 eV respectively. The electron mobility for BTM3 (0.00527), BTM4 (0.005820) and BTM5 (0.00539) are found less than BTP-Cl (0.00643). Similarly, BTM5 gives the least value of hole mobility (0.00558) as compared to BTP-Cl (0.00803). The binding energies of these molecules are also observed less (0.28 eV, 0.29 eV and 0.33 eV for BTM3, BTM4 and BTM5) in gas phase than BTP-Cl (0.35 eV). Also, BTM5 is tested with donor polymer PTB7-Th that provides further evidence for their interactions. It turned out that the structural tailoring at terminals can tune effectively the frontier molecular orbital energy levels, band gap, absorption spectra, open-circuit voltage, reorganization energy and binding energy value in investigated molecules. Our results suggest that the investigated molecules can serve as fine acceptor materials. Additionally, some investigated molecules can also be used as a hole and/or electron transport materials for OSCs.

Characteristics of the Measured First Ionization Potentials of Lanthanides and Actinides

The experimentally determined atomic ionization potentials IP1 of lanthanides and actinides are analyzed. A semiclassical method is used to determine the dependence of the orbital binding energies on the atomic number Z and on quantum numbers. Features revealed for chemical elements with the regularly filled 4f and 5f shells allow approximating the dependences IP1(Z) with an error less than 1% using three fitting parameters for lanthanides and one for actinides, respectively. The revealed features for valence electrons justify a general atomic number scaling law for orbital binding energies, which is valid for both outer and inner electron shells with the regular filling.