Calculation Of Energy Levels Research Articles

Description of collective states in Os192 within the boson expansion theory

The low-lying collective states in $^{192}\mathrm{Os}$ are investigated microscopically by means of the boson expansion theory with the self-consistent effective interactions. The building blocks of the collective boson, the collective potential, and the structures of the wave functions for some relevant states are illustrated. Calculated level energies and electromagnetic properties are compared with the experimental data. Properties of some low-lying states and relevant quasibands are discussed with the help of the boson description of state vectors.

Computational Simulation and Prediction to the Protonated Uranyl-Salophen Coordination with Cyclohexenone

In this study, computer simulation prediction technology was used to establish an interaction model between cyclohexene and protonated small molecules modified uranyl-Salophen. Theoretical simulation research the compounds using Uranyl-Salophen modified by methyl, vinyl and carboxyl-propenyl, with the cyclohexene complexes in vacuum condition, were performed by using density functional theory (DFT) at level with the B3LYP/6-311G*basis set. All of the combination structure is carried out under the same base group, in optimization, infrared spectrum, the binding energy, and the calculation of molecular orbital energy level. The results showed that the capacity and stability of complexes whose Uranyl-Salophen modified by carboxyl-propenyl was strongest, the vinyl followed, and the methyl weakest, and methyl modified even reduce the compounds combining ability.

Fine and hyperfine splitting of the low-lying states of Be9

We perform accurate calculations of energy levels as well as fine and hyperfine splittings of the lowest $^{1,3}\!P_J$, $^{3}\!S_1$, $^{3}\!P^e_J$, and $^{1,3}\!D_J$ excited states of the $^9$Be atom using explicitly correlated Gaussian functions and report on the breakdown of the standard hyperfine structure theory. Because of the strong hyperfine mixing, which prevents the use of common hyperfine constants, we formulate a description of the fine and hyperfine structure that is valid for an arbitrary coupling strength and may have wide applications in many other atomic systems.

Fine structure calculations of excitation energies, lifetimes and radiative properties of S-like Kr XXI

Extensive and systematic calculations for energy levels and lifetimes are carried out for the lowest 145 levels arising from the 3s23p4, 3s3p5, 3s23p33d, 3p6, 3s3p43d and 3s23p23 d2 configurations in S-like Kr XXI ion using the multiconfiguration Dirac-Fock (MCDF) method. Additionally, radiative data such as transition wavelengths, absorption oscillator strengths, line strengths and radiative decay rates have also been computed for electric dipole (E1), electric quadrupole (E2), magnetic dipole (M1) and magnetic quadrupole (M2) transitions from the ground state. The importance of Breit interaction (BI) and quantum electrodynamics (QED) corrections on the energy levels has also been estimated. To assess the credibility and integrity of our MCDF energies, independent calculations using the relativistic configuration interaction (RCI) approach have also been performed. Detailed comparisons are made between our two sets of results, as well as with other existing experimental and theoretical values, and a good agreement is achieved. The present results will be helpful for the modeling and diagnostics of fusion plasmas.

Double‐Sided Graphene‐Enhanced Raman Scattering and Fluorescence Quenching in Hybrid Biological Structures

AbstractDue to their large contact and loading surfaces as well as high sensitivities to chemical changes, graphene‐based materials (GBMs) are increasingly being employed into novel nanomedicine technologies. Here biomolecule—monolayer graphene—kidney tissue hybrid structures are studied using mapping micro‐Raman and fluorescence spectroscopies. Because in this configuration graphene interacts with molecules on both sides, a double‐sided graphene‐enhanced Raman scattering (GERS) effect up to ≈10.1 is found for biomolecules adsorbed on graphene and amino acids in the kidney tissue below graphene. Moreover, graphene causes an efficient autofluorescence quenching (FLQ) up to ≈20% emitted by the kidney tissue. Despite the complexity of such layered materials, the intriguing simultaneous occurrence of double‐sided GERS (a new development of GERS) and FLQ phenomena can be well explained by suitable molecular structure and energy level alignment between molecules and graphene. These result in effective charge transfer mediated by non‐covalent interactions as indicated by correlative strain, doping, and defect analyses in graphene based on the Raman data and energy level calculations. Last, the advantages of using graphene over standard photobleaching are demonstrated. This work can be extended to other macromolecular entities toward integrating GBMs in versatile drug delivery, imaging, and sensing devices.

Symmetric and asymmetric structural evolutions of Te isotopes across the N = 82 shell closure * *Supported by National Natural Science Foundation of China (11875188, 11905130 and 12075169), Sichuan Science and Technology Program (2019JDRC0017), the Doctoral Program of Southwest University of Science and Technology (18zx7147), and Shanghai Sailing Program (19YF1434200)

Systematic calculations of low-lying energy levels, transitions, and g factors of even-even tellurium isotopes with mass numbers from 128 to 140 are performed via the nucleon-pair approximation (NPA) of the shell model with phenomenological multipole-multipole interactions. An optimal agreement is obtained between the calculated results and experimental data. The yrast band structures of nuclei below and above the shell closure are compared and discussed. In particular, the evolutionary differences of values and factors, with respect to the symmetry of , are attributed to the dominant contribution differences in neutron and proton excitations, respectively.

Accurate multiconfiguration calculations of energy levels, lifetimes, and transition rates for Ge XIX

Energy levels, radiative rates and lifetimes for electric-dipole (E1), electric-quadrupole (E2), magnetic-dipole (M1), magnetic-quadrupole (M2) transitions among the lowest 97 levels belonging to the 3s23p2, 3s3p3, 3s23p3d, 3s3p23d, 3s23d2, and 3p4 configurations in silicon-like Ge XIX have been calculated through Multiconfiguration Dirac-Hartree-Fock method. High-accuracy calculations have been performed with accurate treatment of relativity, electron correlation, and quantum electrodynamic effects, as well as inter-electron correlation. The calculated energy levels are in excellent agreement with available experimental data. The present results are reported as benchmarks for future calculations and measurements.

Atomic Structure Calculations of Helium with Correlated Exponential Functions

The technique of quantum electrodynamics (QED) calculations of energy levels in the helium atom is reviewed. The calculations start with the solution of the Schrödinger equation and account for relativistic and QED effects by perturbation expansion in the fine structure constant α. The nonrelativistic wave function is represented as a linear combination of basis functions depending on all three interparticle radial distances, r1, r2 and r = |r→1−r→2|. The choice of the exponential basis functions of the form exp(−αr1−βr2−γr) allows us to construct an accurate and compact representation of the nonrelativistic wave function and to efficiently compute matrix elements of numerous singular operators representing relativistic and QED effects. Calculations of the leading QED effects of order α5m (where m is the electron mass) are complemented with the systematic treatment of higher-order α6m and α7m QED effects.

Statistical Properties of the Transverse-Motion Energy Levels for Channeling Electrons in a Silicon Crystal under Dynamical Chaos Conditions

The classical motion of particles in external fields is frequently chaotic although deterministic within the classical limit. Studying the quantum mechanical behavior of such systems amounts to the problematics of quantum chaos. Quantum chaos manifests itself primarily in the statistical properties of the energy-level arrays of such systems. However, the typical objects under consideration are systems of the type billiards with rigid walls. This paper studies the calculated energy levels of the transverse motion of relativistic electrons in the axial-channeling regime along the [100] direction of the silicon crystal which is described as motion in the smooth potential well. The nearest-level spacing distributions as well as the spectral rigidity are studied for the range of parameters where electron motion is chaotic within the classical limit. Both these characteristics demonstrate agreement with quantum-chaos-theory predictions.

Effect of Tilted Electric Field and Magnetic Field on the Energy Levels, Binding Energies and Heat Capacity of Donor Impurity in GaAs Quantum Dot

The Hamiltonian of an electron confined in a parabolic quantum dot in the presence of perpendicular magnetic field, donor impurity, and tilted electric field, has been solved by employing an exact diagonalization method. All the energy matrix elements have been derived in analytical forms. We have displayed the variation of the computed energy levels, binding energy and heat capacity of the quantum dot with the physical Hamiltonian parameters like: external magnetic and electric fields, confining strength, tilt angle and temperature. It’s found that the binding energy increases as the magnetic field increases. However, it decreases as the electric field increases. The dependence of the heat capacity on the electric field and magnetic fields and impurity has also been investigated. The calculated results show that heat capacity increases as the electric field increases, while it decreases with the enhancement of the magnetic field. In addition, the presence of the donor impurity is found to enhance the heat capacity. The present results are consistent with those reported in the literature.

An approach to determine the diatomic vibrational energy levels: application to LiH, NO and CO molecules

This work presents the systematic calculation of vibrational energy levels, for diatomic molecules through an alternative approach, reposed on the Floquet representation analysis. The Morse potential function has been employed to solve the Schrodinger equation, and to obtain the vibrational energy levels of diatomic systems. As an illustration, the numerical energy values of some molecules have been computed, and compared to those of literature, revealing a good agreement, and showing the accuracy of our approach.

New Mercurated and Tellurated Sulpha Compounds: Synthesis, Invitro Anticancer Study and DFT Calculation.

The current study includes mercuration and telluration of some sulpha compounds; these compounds were prepared by reaction of 4-aminobenzenesulfonic acid and 4,4'-sulfonyldianiline with mercuric(II) acetate reagent to produce Arylmercuric(II)chloride, which was subjected to transmetallation reactions by using TeBr4 to form the Aryltellurium(IV) tribromide. Additionally, the reactions between (2-amino-5-sulfophenyl)mercury(II) chloride and 3,4-dihydroxybenzaldehyde on one hand, and 4,4'-sulfonylbis[2-chloromercuric aniline] with benzaldehyde, on the other, produce mercurated sulpha compounds containing azomethine- group. These obtained compounds react with TeBr4 to form new tellurated sulpha compounds containing azomethine-group. These newly created compounds were subjected to various analyses, including C.H.N.S analysis, proton-NMR, FT-IR, and Carbon-13 NMR. The synthesised compounds were tested for cytotoxicity using in-vitro analyses on two human cancer cell lines, PC3 (prostate cancer cell) and T24 (bladder cancer cell). The prepared organotellurium compounds are effective, especially 4 and 6 compounds. DFT calculations of HOMO and LUMO energy levels and certain quantum parameters indicate that the organomercury compounds are relatively stable and exhibit lesser reactivity when compared to their organotellurium counterparts. Additionally, theoretical results validate the results obtained by the measurement of cancer effectiveness.

Electronic structure of cubic boron arsenide probed by scanning tunneling spectroscopy

The unusually high lattice thermal conductivity of semiconducting cubic boron arsenide (BAs) has motivated studies of the bulk electronic band structure of BAs for its potential use as an active layer material in electronic devices. However, the surface electronic structure of BAs remains to be investigated. Scanning tunneling spectroscopy (STS) is employed here to probe the electronic structure of as-grown and in situ cleaved surfaces of BAs single crystals. The bandgap measured at several interior locations of the cleaved surface is about 2.1 eV, close to our calculated bulk bandgap value of 2.05 eV. In comparison, the measured bandgap within several micrometers from the two edges of the cleaved surface decreases to about 1.9 eV. This decrease is attributed to tunneling from an increased concentration of shallow acceptors. Several of the tunneling peaks observed by STS within the bandgap are close to the calculated energy levels for bulk lattice defects and substitutional impurities. In contrast to some other III–V compound semiconductors where surface relaxation prevents intrinsic surface states from appearing in the bulk bandgap, some measured tunneling peaks in the BAs bulk bandgap can contain contributions from intrinsic surface states calculated for boron dangling bonds.

Large Scale Shell Model Calculations of the Negative-Parity States Structure in 24Mg Nucleus

The negative-parity states of 24Mg nucleus are investigated within the shell model. We are based on the calculations of energy levels, total squared form factors, and transition probability using the p-sd-pf (PSDPF) Hamiltonian in a large model space (0 + 1) hW. The comparison between the experimental and theoretical states showed a good agreement within a truncated model space. The PSDPF-based calculations successfully reproduced the data on the total squared form factors and transition probabilities of the negative-parity states in 24Mg nucleus. These quantities depend on the one-body density matrix elements that are obtained from the PSDPF Hamiltonian. The wave functions of radial one-particle matrix elements calculated with the harmonic-oscillator potential are suitable to predict experimental data by changing the center-of-mass corrections.

Abinitio Calculations of Energy Levels in Be-Like Xenon: Strong Interference between Electron-Correlation and QED Effects.

The strong mixing of close levels with two valence electrons in Be-like xenon greatly complicates abinitio QED calculations beyond the first-order approximation. Because of a strong interplay between the electron-electron correlation and QED effects, the standard single-level perturbative QED approach may fail, even if it takes into account the second-order screened QED diagrams. In the present Letter, the corresponding obstacles are overcome by working out the QED perturbation theory for quasidegenerate states. The contributions of all the Feynman diagrams up to the second order are taken into account. The many-electron QED effects are rigorously evaluated in the framework of the extended Furry picture to all orders in the nuclear-strength parameter αZ. The higher-order electron-correlation effects are considered within the Breit approximation. The nuclear recoil effect is accounted for as well. The developed approach is applied to high-precision QED calculations of the ground and singly excited energy levels in Be-like xenon. The most accurate theoretical predictions for the binding and excitation energies are obtained. These results deviate from the most precise experimental value by 3σ but perfectly agree with a more recent measurement.

Design of All-Fused-Ring Electron Acceptors with High Thermal, Chemical, and Photochemical Stability for Organic Photovoltaics

High-performance donor–acceptor electron acceptors containing 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (INCN)-type terminals are labile toward photooxidation and basic conditions, and ...

Symmetric and Asymmetric Push-Pull Conjugates: Significance of Pull Group Strength on Charge Transfer and Separation.

The effect of acceptor strength on excited-state charge transfer (CT) and charge separation (CS) in central phenothiazine (PTZ)-derived symmetric 1 (PTZ-(TCBD-TPA)2) and asymmetric 2 (PTZ-(TCBD/DCNQ-TPA)2) push-pull conjugates, in which triphenylamine (TPA) acts as end capping and 1,1,4,4-tetracyanobuta-1,3-diene (TCBD) and cyclohexa-2,5-diene-1,4-ylidene-expanded TCBD (DCNQ) act as electron acceptor units, is reported. Due to strong push-pull effects, intramolecular CT was observed in the ground state, extending the absorption into the near-infrared region. Electrochemical, spectroelectrochemical, and computational studies coupled with energy-level calculations predicted both 1 and 2 to be efficient candidates for ultrafast CT. Subsequent femtosecond transient absorption studies along with global target analysis, performed in both polar and nonpolar solvents, confirmed such processes in which the CS was efficient in asymmetric 2, having both TCBD and DCNQ acceptors in polar benzonitrile, while in toluene, only CT was witnessed. This work highlights the significance of the number and strength of electron acceptor entities and the role of solvent polarity in multimodular push-pull systems to achieve ultrafast CS.

Precision nuclear-spin effects in atoms: EFT methods for reducing theory errors

We use effective field theory to compute the influence of nuclear structure on precision calculations of atomic energy levels. As usual, the EFT’s effective couplings correspond to the various nuclear properties (such as the charge radius, nuclear polarizabilities, Friar and Zemach moments etc.) that dominate its low-energy electromagnetic influence on its surroundings. By extending to spinning nuclei the arguments developed for spinless ones in Burgess, et al. (2018), we use the EFT to show – to any fixed order in Zα (where Z is the atomic number and α the fine-structure constant) and the ratio of nuclear to atomic size – that nuclear properties actually contribute to electronic energies through fewer parameters than the number of these effective nuclear couplings naively suggests. Our result is derived using a position-space method for matching effective parameters to nuclear properties in the EFT, that more efficiently exploits the simplicity of the small-nucleus limit in atomic systems. By showing that precision calculations of atomic spectra depend on fewer nuclear uncertainties than naively expected, this observation allows the construction of many nucleus-independent combinations of atomic energy differences whose measurement can be used to test fundamental physics (such as the predictions of QED) because their theoretical uncertainties are not limited by the accuracy of nuclear calculations. We provide several simple examples of such nucleus-free predictions for Hydrogen-like atoms.

Calculation of rovibrational eigenstates of H3+ using ScalIT

H 3 + is a key player in molecular astrophysics, appearing in the interstellar medium and in the atmospheres of gas giants. It also plays an important role in star formation, and it has also been detected in supernova remnants. In theoretical chemistry, H3+ has long been a benchmark polyatomic system for high-level electronic-structure computations, as well as for quantum dynamics studies. In this work, exact quantum dynamical calculations are carried out for H3+, using the ScalIT suite of parallel codes, applied to two spectroscopically accurate potential energy surfaces. Specifically, rovibrational energy levels and wavefunctions are computed and labeled. Sixty vibrational states (for J = 0) are first determined, and then, rotational excitations for each of these “vibrational parent” states are computed up to total angular momentum J = 46, which is the highest value for which bound states of this molecule exist (D0 ∼ 35 000 cm−1). For these calculations, a very tight basis set convergence of a few 10−4 cm−1 (or less) has been achieved for almost all the computed energy levels. Where comparisons can be made, our results are found to agree well with earlier calculations and experimental data.

Defect and Impurity-Complex Depassivation During Electron-Beam Irradiation of GaAs

Significant increases in thermal generation rates in molecular-beam epitaxy (MBE)-grown p-i-n-i-p GaAs structures are attributed to depassivation of hydrogen-defect/impurity complexes during high-intensity, low-energy electron-beam irradiation. Quantum calculations of relevant defect energy levels and reaction pathways suggest that depassivation of oxygen impurities is the likely cause of the observed degradation. Electric-field and excess-carrier-induced dehydrogenation of O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">As</sub> -H complexes is identified as a likely rate-limiting process, leading to the observed enhanced thermal carrier generation in these structures.