Detachment Energies Research Articles

Quantum Computation of Hydride Ion using Variational Quantum Algorithm

AbstractBecause of remarkable reactivity and strong electron‐electron correlation effects, the precise prediction of ground state energy and chemical reactivity of hydride ion is an essential objective in quantum chemistry. Leveraging variational quantum algorithms offers a promising avenue for studying molecular properties using current noisy intermediate‐scale quantum devices. This work utilises the variational approach to anticipate the ground state, reactivity, and single‐electron detachment energy of the three‐body hydride ion. We investigated both Hardware‐Efficient Ansatz (HEA) and Chemistry‐inspired ansatz based on a Unitary Coupled Cluster (UCC) on both noiseless and noisy IBM simulators. Modern error‐mitigating techniques, such as Zero‐Noise Extrapolation (ZNE) with unitary folding and measurement error mitigation, have been implemented to significantly reduce errors in noisy environments. This study contributes to our understanding of the quantum computational nuances of the hydride ion and addresses the question of whether quantum computers can retain the correlation energies for these correlated ions.

Dispersion leading potential energy surface of N2·NbN12-: Anion photoelectron spectroscopy and theoretical studies.

In order to understand the dispersion interactions between molecules and to provide information about the potential energy surface of geometry evolutions, NbN12- and N2·NbN12- complexes were investigated by using photoelectron spectroscopy and abinitio calculations. The experimental adiabatic detachment energy (ADE) and vertical detachment energy (VDE) of NbN12- were both measured to be 2.129 ± 0.030eV. The experimental ADE and VDE of N2·NbN12- were measured to be 2.17 ± 0.05 and 2.23 ± 0.05eV, respectively, which are slightly higher than those of NbN12-. The structures of NbN12-/0 were confirmed to be hexacoordinated octahedrons. The investigation of N2·NbN12- structures shows that it is stable for N2 to bind to the face or vertex site of octahedron NbN12-; the face-side-on structure has the lowest energy. The calculations based on symmetry-adapted perturbation theory suggest that the dispersion term is predominant and leads to the stability of N2·NbN12- complexes.

Reactivity of Polynuclear Niobium Oxynitride Cluster Anions Nb4N5-xOx - (x=0-5) toward N2.

The activation of N₂ under mild conditions remains a significant challenge in chemistry. Understanding how the composition of ligands modulates the reactivity of metal centers is pivotal for the rational design of efficient catalysts for nitrogen fixation. Herein, the reactions between polynuclear niobium oxynitride anions Nb4N5-xOx - (x=0-5) and N2 were investigated by employing mass spectrometry, photoelectron imaging spectroscopy, and theoretical calculations. The rate constants of Nb4N5-xOx -/N2 gradually decrease for x=0 to x=4, and then increase again for x=5. The sharp increase of the rate constants of Nb4O5 -/N2 corresponds to a decrease in the electron detachment energy of the Nb4O5 - cluster in the photoelectron spectroscopic experiments. Theoretical calculations suggest that the low-coordinated Nb-Nb sites in Nb4N5-xOx - (x=0-5) behaves as the active centers to bind N2 in the side-on/end-on manner. Mechanistic analysis reveals that reducing the N/O ratio leads to higher electron densities on the active Nb-Nb centers and decreased positive charge on the metal atoms, which hinders the approach of N2 to the clusters. This finding discloses fundamental insights into the impact of N/O ratio in fine-tuning the reactivity of metal centers toward N2 adsorption in related catalytic processes.

Anion photoelectron spectroscopy and chemical bonding of ThS2- and ThSO.

Anion photoelectron spectra of ThSO- and ThS2- were recorded using the third (355nm) harmonic of an Nd-YAG laser; these provided the measured vertical detachment energies of each anion. The experiments are supported by extensive coupled cluster calculations on ThSO, ThSO-, ThS2, and ThS2-, as well as the oxygen congeners ThO2 and ThO2-. The abinitio calculations, which included complete basis set extrapolations, spin-orbit effects using four-component coupled cluster, and higher-order correlation contributions through CCSDT(Q), yielded an adiabatic electron affinity for ThO2 that was within 0.02eV of the previously determined experimental value. The singly occupied molecular orbital (SOMO) in all three anions corresponds primarily to the 7s orbital on Th. Successive substitution of S for each O in ThO2 leads to larger electron affinities and smaller bond angles in the neutral molecules, but larger angles in the anions. As demonstrated by Franck-Condon simulations of the spectra using the CCSD(T) spectroscopic constants, substitution of O by S significantly complicates the resulting detachment spectra due to the lower vibrational frequencies in the sulfur species. Overall the calculated vertical detachment energies are in very good agreement with the experiment. In addition to the adiabatic electron affinities of each species, atomization energies and heats of formation have also been determined via the FPD approach with expected uncertainties of 1-2 kcal/mol.

Anions Formed by Perchlorofluorobenzenes C6ClnF6-n (n = 0-6).

Anions formed by the perhalobenzene series C6ClnF6-n (n = 0-6) are studied computationally. All members of the series form both stable valence and stable nonvalence anions. At the geometry of the neutral parents, only nonvalence anions are bound, and the respective vertical electron affinities show values in the 20 to 60 meV range. Valence anions show distorted nonplanar structures, and one can distinguish two types of conformers. A-type conformers show puckered-ring structures and excess electrons delocalized over several C-Cl bonds [in the case of C6F6-, C-F bonds], while B-type conformers possess excess electrons essentially localized in a single C-Cl bond, which is accordingly strongly stretched and bent out of plane. For a specific anion, all conformers are close in energy (relative energies of less than 10 kJ/mol) and are connected by low-lying transition states. Accordingly, A-type and B-type conformers possess similar adiabatic electron affinities; however, their vertical detachment energies exhibit drastically different values, which should ease conformer distinction in photoelectron spectroscopy.

Photoelectron spectroscopy of deprotonated benzonitrile.

The recent discovery of cyano-substituted aromatic and two-ring polycyclic aromatic hydrocarbon molecules in Taurus Molecular Cloud-1 has prompted questions on how the electronic structure and excited-state dynamics of these molecules are linked with their existence and abundance. Here, we report a photodetachment and frequency- and angle-resolved photoelectron spectroscopy study of jet-cooled para-deprotonated benzonitrile (p-[Bzn-H]-). The adiabatic detachment energy was determined as 1.70 ± 0.01eV, in good agreement with CCSD(T)/aug-cc-pVTZ calculations. The spectra across the first few electron-volts above threshold are dominated by prompt autodetachment processes associated with excitation of at least five short-lived (tens of femtoseconds) temporary anion shaped resonances since excitation cross sections are several orders of magnitude larger than direct photodetachment cross sections. The photoexcitation vibronic profile is dominated by a ≈640 cm-1 ring deformation mode. [Bzn-H]- lacks a valence-localized excited state situated below the detachment threshold and does not exhibit thermionic emission following excitation of the temporary anion resonances. Thus, [Bzn-H]- is unlikely to be stable in many interstellar environments.

Facet-Dependent Lethality of a Contact Insecticide Crystal.

The activity of crystalline contact insecticides relies on the extraction of surface molecules by insect tarsi upon contact. Most crystals are inherently anisotropic, and surface molecules on symmetry independent faces are expected to have different free energies. The facet-dependent bioavailability and associated efficacy of insect lethality have not been investigated, however. We discriminate the bioactivity of various facets of single crystals of DDT (1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane), a well-known contact insecticide. Our findings reveal facet-dependent lethality differences of nearly 75% among four crystallographically unique facets. Furthermore, computations reveal that the respective lethalities of the facets are strongly correlated with the detachment energies of molecules from the crystal surfaces. This facet-dependent lethality suggests a pathway to enhance the efficacy of known contact insecticides through crystal habit control.

Bubble adhesion dynamics on solid surfaces: Interfacial behavior, force, and energy perspectives using a self-developed dynamic force testing system

Bubble-solid surface adhesion is crucial for industrial processes such as wastewater treatment, and the separation of minerals, plastics, and biomass. In this paper, a novel dynamic force testing system was developed to provide a detailed understanding of bubble-solid adhesion dynamics by simultaneously collecting “time-displacement-force” signals and capturing real-time images. The interfacial behavior and force mechanisms of bubble adhesion to solid surfaces with varying hydrophobicity were investigated. Higher hydrophobicity results in more pronounced “snap-in” adhesion and greater adhesion strength. Instead of fully detaching, bubble breaks at the capillary neck and leaves a microbubble on the solid surface, whose size increases with hydrophobicity, indicating different interfacial behaviors in subsequent reaction. The evolution of Laplace force and surface tension force was further analyzed and the toroidal approximation shows over 60 μN error in Laplace force calculation for large bubble deformations. Thus, for the first time, the “gorge” method was employed to calculate the bubble adhesion force in the presence of a capillary neck. Error analysis indicates that this method, while maintaining simplicity, achieved higher accuracy (lower error) by calculating the Laplace force based on the neck area and accounting for the surface tension force along the tangent at the neck. Energy analysis show that the detachment energies in the stretching and sliding phases correspond to the energy barrier to be overcome for detachment and the “effective work” of interfacial change, respectively. This provides new insights into detachment mechanisms and industrial process modelling, such as flotation.

Detachment Energy Evaluation in Nano-Particle Cleaning Using Lateral Force Microscopy

Detachment Energy Evaluation in Nano-Particle Cleaning Using Lateral Force Microscopy

Strongly bound anions featuring bismuth fluoride building blocks

The stability of polynuclear superhalogen anions composed of BiF5 building blocks was investigated using ab initio electronic structure methods and flexible basis sets. A comprehensive exploration of the ground state potential energy surfaces of (Bi2F11)−, (Bi3F16)− and (Bi4F21)− anions, which can be viewed as comprising BiF5 fragments and an additional fluorine atom, led to the identification of their isomeric structures. It was found that the most stable isomers, predicted to dominate at room temperature, correspond to chain-like extended structures containing BiF6 subunits, with fluorine ligands arranged octahedrally around Bi atoms, sharing F atoms to form Bi–F–Bi bridging linkages. The vertical electron detachment energies of the (BinF5n+1)− anions (n = 1–4) were found to be very high (ranging from 10.91 to 13.36 eV) and increased with the number of bismuth atoms (n) and thus the BiF5 building blocks involved in the structure. Thermodynamic stability of the (BinF5n+1)− anions (i.e., their susceptibility to fragmentation) was also verified and discussed.

Theoretical exploration of the effects of alkali metal atoms on the structures and electronic properties of silicon clusters

The effects of alkali metals (Li, Na, K, Rb) on the geometric configurations and electronic properties of silicon clusters Sin− (n = 3 − 16) were studied through a genetic algorithm code coupled with density functional theory (DFT) calculations. Almost all of these AMSin− clusters share the same configurations and adopt the ground-state Sin− clusters as the structural motifs with the AM atoms adsorbed on the surface without severely distorting their structures. All Li, Na, K and Rb atoms act as electron donors in all these clusters as that of Cs atoms in CsSin− clusters. These AMSin− clusters possess similar electronic properties from the results of the on-site charges, vertical detachment energies (VDEs), HOMO-LUMO gaps, average binding energies, and secondary energy differences, especially for AM=K, Rb and Cs with closed values. Sizes n = 5, 10 and 13 for all these AMSin− and pure Sin− clusters are magic numbers.

Energetics and spectroscopic studies of clusters and the temperature dependencies of the isomers: An approach based on a combined recipe of parallel tempering and quantum chemical methods.

A system associated with several number of weak interactions supports numerous number of stable structures within a narrow range of energy. Often, a deterministic search method fails to locate the global minimum geometry as well as important local minimum isomers for such systems. Therefore, in this work, the stochastic search technique, namely parallel tempering, has been executed on the quantum chemical surface of the system for -8 to generate global minimum as well as several number of local minimum isomers. IR spectrum can act as the fingerprint property for such system to be identified. Thus, IR spectroscopic features have also been included in this work. Vertical detachment energy has also been calculated to obtain clear information about number of water molecules in several spheres around the central anion. In addition, in a real experimental scenario, not only the global but also the local minimum isomers play an important role in determining the average value of a particular physically observable property. Therefore, the relative conformational populations have been determined for all the evaluated structures for the temperature range between 20K and 400K. Further to understand the phase change behavior, the configurational heat capacities have also been calculated for different sizes.

Electron Binding Energies of Open-Shell Species from Diagonal Electron-Propagator Self-Energies with Unrestricted Hartree-Fock Spin-Orbitals.

For closed-shell molecules, valence electron binding energies may be calculated accurately and efficiently with ab initio electron-propagator methods that have surpassed their predecessors. Advantageous combinations of accuracy and efficiency range from cubically scaling methods with mean errors of 0.2 eV to quintically scaling methods with mean errors of 0.1 eV or less. The diagonal self-energy approximation in the canonical Hartree-Fock basis is responsible for the enhanced efficiency of several methods. This work examines the predictive capabilities of diagonal self-energy approximations when they are generalized to the canonical spin-orbital basis of unrestricted Hartree-Fock (UHF) theory. Experimental data on atomic electron binding energies and high-level, correlated calculations in a fixed basis for a set of open-shell molecules constitute standards of comparison. A review of the underlying theory and analysis of numerical errors lead to several recommendations for the calculation of electron binding energies: (1) In calculations that employ the diagonal self-energy approximation, Koopmans's identity for UHF must be qualitatively correct. (2) Closed-shell reference states are preferable to open-shell reference states in calculations of molecular ionization energies and electron affinities. (3) For molecular electron binding energies between doublets and triplets, calculations of electron detachment energies are more accurate and efficient than calculations of electron attachment energies. When these recommendations are followed, mean absolute errors increase by approximately 0.05 eV with respect to their counterparts obtained with closed-shell reference orbitals.

Cl©Li5Cl5-: A Star-like Superhalogen Anion Featuring a Planar Pentacoordinate Chlorine at the Center.

Among the known planar pentacoordinate atoms, chlorine is missing due to its large radius and high electronegativity. Herein, we report the first star-like superhalogen anion D5h Cl©Li5Cl5- (1), which contains a planar pentacoordinate chlorine (ppCl) at the center. Computer structural searches and high-level calculations reveal that 1 is a true global minimum (GM) on the potential energy surfaces. Molecular dynamics simulations indicate it is kinetically stable against isomerization or decomposition. Although detailed chemical bonding analyses reveal one delocalized 6c-2e σ bond over the Cl©Li5 central unit and five delocalized 3c-2e σ bonds along the periphery, while aromaticity has very little beneficial effect on stability, instead, ionic interaction dominates the stability of the system. More encouragingly, with the large HOMO-LUMO energy gap of 7.66 eV and vertical detachment energy of 7.87 eV, the highly chemically inert 1 can be viewed as a typical superhalogen anion and is possible to be synthesized and characterized in future experiments.

A comprehensive study on three typical photoacid generators using photoelectron spectroscopy and abinitio calculations.

Conducting a comprehensive molecular-level evaluation of a photoacid generator (PAG) and its subsequent impact on lithography performance can facilitate the rational design of a promising 193nm photoresist tailored to specific requirements. In this study, we integrated spectroscopy and computational techniques to meticulously investigate the pivotal factors of three prototypical PAG anions, p-toluenesulfonate (pTS-), 2-(trifluoromethyl)benzene-1-sulfonate (TFMBS-), and triflate (TF-), in the lithography process. Our findings reveal a significant redshift in the absorption spectra caused by specific PAG anions, attributed to their involvement in electronic transition processes, thereby enhancing the transparency of the standard PAG cation, triphenylsulfonium (TPS+), particularly at ∼193nm. Furthermore, the electronic stability of PAG anions can be enhanced by solvent effects with varying degrees of strength. We observed the lowest vertical detachment energy of 6.6eV of pTS- in PGMEA solution based on the polarizable continuum model, which prevents anion loss at 193nm lithography. In addition, our findings indicate gas-phase proton affinity values of 316.4 kcal/mol for pTS-, 308.1 kcal/mol for TFMBS-, and 303.2 kcal/mol for TF-, which suggest the increasing acidity strength, yet even the weakest acid pTS- is still stronger than strong acid HBr. The photolysis of TPS+-based PAG, TPS+·pTS-, generated an excited state leading to homolysis bond cleavage with the lowest reaction energy of 83 kcal/mol. Overall, the PAG anion pTS- displayed moderate acidity, possessed the lowest photolysis reaction energy, and demonstrated an appropriate redshift. These properties collectively render it a promising candidate for an effective acid producer.

Confined Z-Pinch Magnetic Nozzle : A New Approach to Space Propulsion System that Utilizes Trapped Charged Particles

This paper provides a theoretical overview of a Z-pinch magnetic nozzle plasma propulsion system designed for Low Earth Orbit (LEO). The system utilizes trapped charged particles from the spacecraft's environment and magnetic confinement to generate thrust, reducing the need for onboard propellants. By employing a magnetic mirror configuration, the plasma is confined and accelerated to create propulsion. The proposed propulsion system is tailored to function in the dynamic space radiation environment of LEO, particularly in polar orbits, accounting for variations in solar activity that affect trapped protons and electrons. The mechanism involves converting magnetic plasma energy into directed kinetic energy, facilitating efficient plasma detachment and momentum transfer to the spacecraft. This study examines the feasibility, design overview, and constraints of implementing this propulsion technology. Key challenges include the variability of the space environment, technological complexities, radiation effects, plasma detachment efficiency, energy requirements, and material durability. Overcoming these challenges through innovative engineering and rigorous testing is essential for successful implementation. The Z-pinch magnetic nozzle plasma propulsion system promises to advance space propulsion technology, offering a more efficient and cost-effective method for satellite operations in LEO. With further research and development, it has the potential to support future satellite missions and space exploration initiatives.

Structural evolution and electronic properties of anionic plutonium-doped oxygen clusters

Plutonium oxides are important in actinide chemistry and nuclear industry activities, and the demand and interest in enriching knowledge of plutonium chemistry is growing increasingly significant. However, unlike uranium oxide clusters, few studies related to the geometry and bonding properties of anionic plutonium oxide clusters have been reported. Here we explored the geometries, photoelectron spectra, and electronic properties of anionic plutonium oxide clusters by means of unbiased structural searches coupled with density-functional theory (DFT). The results show that the PuO6− cluster with a high D2h symmetry formed by a linear O-Pu-O plutonyl unit with two O2 units exhibits excellent stability. In addition, the HOMO–LUMO gap value of PuO6− cluster are 4.35 eV and 3.41 eV for the α- and β-orbitals, respectively, as well as the vertical detachment energy (VDE) of 4.20 eV. In the analysis of molecular orbitals and adaptive natural density partitioning in oxygen-rich systems, the σ bonds between plutonium atom and oxygen ligands, primarily from the Pu-5f and O-2p orbitals, are responsible for the goodish stability of PuO6− cluster. We hope that the current work can enrich the geometrical configuration of plutonium oxide oxygen clusters and provide reference information for the subsequent research work.

Probing the geometric and electronic structure of rhodium oxide clusters (RhO)n− (n = 2–4) by anion photoelectron spectroscopy and theoretical calculations

The cluster configurations of (RhO)n− (n = 2–4) have been examined using photoelectron (PE) velocity-map imaging combined with density functional theory calculations. The PE spectra have provided the anion detachment energies (ADEs) information of three ground states, determined to be 2.40, 2.86, and 2.94 eV for n = 2–4, respectively. The geometric structures have been identified by comparing the density of states (DOS) spectra of several low-lying isomers with the PE spectra. The three cluster configurations consist of a Rhn (n = 2–4) core with isolated O atoms bonded to the core, exhibiting planar or quasi-planar geometries. The analysis of magnetic moments and spin densities indicated that the most stable three anions have high spin multiplicities of 4, 5, and 4 for n = 2–4, respectively, with the unpaired electrons delocalized on each of the Rh and O atoms.

Highly crystalline poly-3-hexylthiophene particles prepared from Pickering emulsions stabilized by alkylamine functionalized graphene quantum dots

Pickering emulsions have received much attention due to their high emulsions stability and ability to form functional emulsions compared to conventional emulsions. The stability of Pickering emulsions is dependent on the geometry and wettability of the particle type emulsifiers, which affect the detachment energy at the interface. Therefore, surface property control of the particle is essential. The graphene quantum dots (GQDs) functionalized with octylamine (C8), dodecylamine (C12), and hexadecylamine (C16) were synthesized and the stability of oil-in-water type Pickering emulsions compared. The detachment energies of the Pickering emulsifiers were calculated by measuring their wettability. Crystalline poly-3-hexylthiopene nanoparticles (P3HT NPs) were synthesized from the Pickering emulsion with C12-GQDs. Among the three GQDs, the C12-GQDs formed the most stable Pickering emulsions at the water-CHCl3 interface because of an appropriate balance between the water and oil phases due to the highest detachment energy. High-crystalline P3HT NPs can be synthesized from the Pickering emulsion with C12-GQDs due to the slower solvent evaporation and enhanced stability.

NH4+][BxH3x+1-] (x = 1-5): Role of Polynuclear Superhalogens in High-Capacity Hydrogen Storage.

Superhalogen anions are characterized by a higher vertical detachment energy (VDE) than those of halides. Ammonium borohydride, [NH4+][BH4-], is a potential candidate for high-capacity hydrogen storage but is not practically used due to its instability against dissociation to ammonia borane. Interestingly, BH4- is a superhalogen anion, and therefore, we use polynuclear BxH3x+1- superhalogen anions and study [NH4+][BxH3x+1-] complexes for x = 2-5 using density functional theory. The gravimetric hydrogen density of these complexes is smaller than that of [NH4+][BH4-] only slightly. We calculate the dehydrogenation energy and the Gibbs free energy of [NH4+][BxH3x+1-] complexes through ammonia borane. We notice that these complexes are more stable than [NH4+][BH4-], whose stability increases with an increase in x. The enhanced stability of [NH4+][BxH3x+1-] complexes appears as a consequence of the increase in the VDE of polynuclear BxH3x+1- superhalogen anions. We believe that these findings might attract experimentalists to synthesize these complexes.