Calculation Of Energy Levels Research Articles

Relativistic atomic structure calculations and study of plasma parameters for Na-like Se XXIV

Extensive calculations of energy levels and radiative data such as transition wavelengths, radiative rates, oscillator strengths, and line strengths for electric dipole (E1) transitions have been performed for Se XXIV using the multiconfiguration Dirac–Fock method. For other types of transitions, namely, magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2), only the radiative rates (A) are listed. The importance and effect of valence-valence and core-valence correlations on the excitation energies have been studied. For additional accuracy assessments, analogous calculations have been carried out by employing the flexible atomic code and configuration interaction technique. Comparisons are made with the available experimental and theoretical data in the literature. Close agreement has been found ensuring the accuracy and reliability of our results. The effect of plasma temperature on the line intensity ratio, electron density, plasma frequency, and skin depth has been analyzed for hot dense plasma (HDP) in local thermodynamic equilibrium. The present work might be beneficial in the modeling and characterization of HDP.

Evidence for a Jeff=0 ground state and defect-induced spin glass behavior in the pyrochlore osmate Y2Os2O7

We present AC and DC magnetometry, heat capacity, muon spin relaxation ($\mu$SR) and resonant inelastic X-ray scattering (RIXS) studies of the pyrochlore osmate Y$_2$Os$_2$O$_7$. We observe a non-zero effective moment governed by $\sqrt{f}\mu_{\rm{eff}} = 0.417(1)\,\mu_{\rm{B}}$ where $f$ is the fraction of Os sites which exhibit a spin, and spin freezing at temperature $T_{\rm f} \simeq 5\,$K, consistent with previous results. The field dependence of magnetisation data shows that the paramagnetic moment is most likely due to large moments $\mu_{\rm eff} \simeq 3\,\mu_{\rm B}$ on only a small fraction $f \simeq 0.02$ of Os sites. Comparison of single-ion energy level calculations with the RIXS data yields a non-magnetic $J_{\rm eff} = 0$ ground state on the Os$^{4+}$ sites. The spin-orbit interaction, Hund's coupling and trigonal distortion of OsO$_{6}$ octahedra are all important in modelling the experimentally observed spectra. We are able to rule out impurity effects, leaving disorder-related effects such as oxygen non-stoichiometry or site interchange between Os and Y ions as the most plausible explanation for the magnetic response in this material.

Nuclear energy levels in 58Ni

Energy levels, total angular momenta and parity for two nucleons that present outside closed core 56Ni (Nickel) which occupied FP nuclear shell have been calculated using nuclear shell model application. We have used FP M3YE interaction to calculate energy levels of 58Ni, in addition, the results are compared with experimental data, modified surface delta interaction (MSDI), Reid's potential (RP) and non-zero pairing shell model (NZPSM).
 Harmonic Oscillator potential is used to generate single particle wave functions in FP shell and considering as an inert core.
 Oxford Buenos Aires Shell Model (OXBASH) code for nuclear shell model calculation has been utilized to carry out the calculations and comparison with experimental data had been done.

Precise Computation of Energy Levels and Radiative Lifetimes in the s, p, d, and f Sequence of Hydrogen Isotope, with Natural Line Widths

Energy levels and Radiative lifetimes in Deuterium for the following: ns 2 S 1/2 (n≥2), np 2 P o (1/2,3/2) (n≥2), nd 2 D (3/2,5/2) (n≥3), and nf 2 F o (5/2,7/2) (n≥4) sequence have been evaluated with uncertainties in energies caused due to uncertainty principal. Theoretical calculations performed utilizing the Weakest Bound Electron Potential Model Theory (WBEPMT). Both sets of data show quite an excellent agreement with the experimental data listed at NIST. This theoretical computation is also a continuation of the work by Raza. S. et al. in Neutral Hydrogen. The high ‘n’ (principal quantum number) values for both sets of data are presented very first time by utilizing WBEPMT. Keywords: Energy levels, Radiative lifetimes, Quantum defects, Weakest bound electron, Natural line width. DOI : 10.7176/JNSR/9-10-07 Publication date :May 31 st 2019

Relaxation Processes in Submicron Heterotransistors with a System of Quantum Wells

The analysis of relaxation processes in submicrometer heterostructure transistors with the system of quantum walls is investigated. The methods of nano heterostructure design are developed including quantum effects and specific for ternary alloys scattering mechanism. Modeling based on the relaxation equations system for submicrometer heterostructures with quantum walls is fulfilled.The optical, acoustic, intervalley and doping scattering mechanisms is considered. New approach allows to study the influence of alloy scattering as well as. The relaxation times are expected for scattering mechanisms and the influence on field-speed and output characteristics of submicrometer heterostructure transistor are estimated.The modeling results take into account influence of casual fluctuations of the molar concentration of aluminium in the structure of transistor. The analysis of the scattering mechanisms is considered in the 2D-model of structure, that allows to estimate influence of the separate scattering mechanisms on the electronic gas in heterostructures with the systems of quantum walls. Polar optical phonons scattering is basic in such structures, while in an area gate-drain does not begin to prevail the intervalley scattering mechanism.It is shown that the average drift speed in the heterotransistor with two channel structure are more high, than in heterotransistor with one potential wall and two heterojunctions transistors have higher values of output current.The growth of the average drift speed in a structure with two quantum walls in comparison from heterotransistor with one quantum walls makes to 30-40%. It is related to the redistribution of electrons between potential walls with the loss of the energy at overcoming of barriers.The modeling results shown that warming-up of electronic gas and growth of the electrons temperature is a greater degree related to the electrons which drift in potential walls at heterojunctions.It is also necessary to take into account the dimensional quantization effect. This effect in heterostructure is require the calculation of discrete energy levels in quantum walls.Diminishing of the influence of strong electric-field effects in a two channel structure is related to the diminishing of scattering probability both on polar optical phonons and as a result of the injecting of electrons to lower heterojunction with high initial speed and small values of energy which diminishes also probability of the intervalley scattering.The model of calculation of the quantum walls influence on the longitudinal transport in the heterojunction transistors with submicrometer gate length are developed. The mathematical model can be used for the calculation of not only heterostructures transistor but also other constructions of multi-layered devices with the systems of quantum walls in the conditions of the strong electric fields.Ref. 13, fig. 19.

Theoretical study of the electron structure of superheavy elements with an open 6d shell: Sg, Bh, Hs, and Mt

We use recently developed efficient versions of the configuration interaction method to perform {\em ab initio} calculations of the spectra of superheavy elements seaborgium (Sg, $Z=106$), bohrium (Bh, $Z=107$), hassium (Hs, $Z=108$) and meitnerium (Mt, $Z=109$). We calculate energy levels, ionization potentials, isotope shifts and electric dipole transition amplitudes. Comparison with lighter analogs reveals significant differences caused by strong relativistic effects in superheavy elements. Very large spin-orbit interaction distinguishes subshells containing orbitals with a definite total electron angular momentum $j$. This effect replaces Hund's rule holding for lighter elements.

Accurate study on the properties of spectral lines for Na-like Cr13+

An extended calculation of energy levels, radiative rates, and lifetimes are reported for sodium-like chromium. Extensive configuration interaction calculations have been performed using general-purpose relativistic atomic structure package (GRASP). The radiative rates, oscillator strengths, and line strengths are listed for all electric dipole (E1) transitions. However, for magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions, only radiative rates are listed. The importance of valence–valence (VV) and core–valence (CV) correlation effects in the calculation of energy levels have also been shown. To confirm the accuracy of the present results for energy levels by GRASP, independent calculations have been performed by using Flexible Atomic Code (FAC) and configuration interaction method (CIV3). The accuracy of the present levels, wavelengths, transition rates, and lifetimes are assessed by comparing them to available experimental and other theoretical results. We believe that our extensive results may be beneficial in fusion plasma research and astrophysical investigations and applications.

Nuclear structure study of [22,24]Ne and [24]Mg nuclei

Shell model calculations based on large basis has been conducted to study the nuclear structure of $^{20}Ne$, $^{22}Ne$ and $^{24}Mg$ nuclei. The energy levels, inelastic electron scattering form factors and transition probabilities are discussed by considering the contribution of configurations with high-energy beyond the model space of sd-shell model space which is denoted as the core polarization (CP) effects.~The Core polarization is considered by taking the excitations of nucleus from the $1s$ and $1p$ core orbits and also from the valence $2s$ $1d$ shell orbit in to higher shells with $4\hbar\omega$. The effective interactions $USDA$ and $USDB$ are employed with $sd$ shell model space to perform the calculation and the core polarization are calculated with $MSDI$ as residual interaction.~The calculated energy level schemes, form factors and transition probabilities were compared with the corresponding experimental data. The effect of core polarization is found very important for the calculation of $B(C2)$, $B(C4)$ and form factors, and gives excellent results in comparison with the experimental data without including any adjustable parameters.

Atomic structure and excitation cross section by electron impact of tungsten ions, W38+

Excitation energies, radiative rates, and cross sections of tungsten ions (W38+) by electron impact have been calculated using the multiconfiguration Dirac–Fock and R-matrix methods for a configuration state list, which consists of , and and f. A set of configuration state functions with double excitations up to 5l orbitals have been included within the calculations of energy levels and transition probabilities. R-matrix calculations of collision strength and cross section have been executed for the intercombination transitions between 4d, and 4p54f. Resonance collision strengths have been observed at low energies of incident electrons in the range of ∼5−40 Ryd; however, the strong lines limited between 12−25 Ryd. To estimate the accuracy of the calculated energy levels and transition probabilities, comparisons with experimental observations and theoretical calculations are presented, and between different methods for collision strengths and cross sections, as well.

Extended Calculations of Energy Levels and Transition Rates of Nd ii-iv Ions for Application to Neutron Star Mergers

Abstract The coalescence of a binary neutron star gives rise to electromagnetic emission, known as a kilonova, that is powered by radioactive decays of r-process nuclei. Observations of a kilonova associated with GW170817 provide a unique opportunity to study heavy element synthesis in the universe. However, the atomic data of r-process elements are not yet complete enough to decipher the light curves and spectral features of kilonovae. In this paper, we perform extended atomic calculations of neodymium (Nd, Z = 60) to study the impact of the accuracy in atomic calculations on astrophysical opacities. By employing multiconfiguration Dirac–Hartree–Fock and relativistic configuration interaction methods, we calculate the energy levels and transition data of electric dipole transitions for Nd ii, Nd iii, and Nd iv ions. Compared with previous calculations, our new results provide better agreement with the experimental data. The energy level accuracies achieved in the present work are 10%, 3%, and 11% for Nd ii, Nd iii, and Nd iv, respectively, compared to the NIST database. We confirm that the overall properties of the opacity are not significantly affected by the accuracies of the atomic calculations. The impact on the Planck mean opacity is up to a factor of 1.5, which affects the timescale of kilonovae by at most 20%. However, we find that the wavelength-dependent features in the opacity are affected by the accuracies of the calculations. We emphasize that accurate atomic calculations, in particular for low-lying energy levels, are important to provide predictions of kilonova light curves and spectra.

Experimental and theoretical studies of the structural, electronic and optical properties of BCzVB organic material

1,4-Bis[2-(3-N-ethylcarbazoryl)-vinyl]benzene (BCzVB) organic molecule in different solvents have been performed to explore its electronic structure and photophysical properties using solution technique and quantum chemistry calculations. The calculated energy levels of the BCzVB in solvent environments range from -5.04 to -5.06 eV (HOMO) and from -1.87 to -1.93 eV (LUMO). Solvent environment enhanced characteristic properties of the BCzVB. The performance of functional CAM-B3LYP and B3LYP was compared with measured the ultraviolet-visible (UV–vis) and charge transport properties. The refractive index was calculated using measured energy gap data. The atomic charges, dipole moments, total energies, lowest vibrational frequencies and radial distribution functions (RDFs) were searched. The reflectance spectra of the BCzVB solutions were also measured. From the results obtained, the BCzVB material has considerable potential for sensitivity, diode and OLED applications.

Isotope shifts and band progressions in SO2 rovibrational energy levels: using quantum theory to extract rotational constants

ABSTRACTWe report the isotope shifts of the rotational constants and vibrational band progressions of the sulfur dioxide molecule (SO), for all four stable sulfur isotopes32S,33S,34S, and36S. These are extracted from exact quantum theoretical calculations of the SO rovibrational energy levels, as reported in Chem. Phys. 450–451, 59 (2015) and Chem. Phys. 461, 34 (2015) and by fitting these levels to a J-shifting (JS)-type scheme, applied to a representative set of total angular momentum (J) values. The approach used to obtain the rotational constants is unusual in that it is derived directly from the quantum theoretical framework used for the earlier calculation, which gives rise to a flexible (i.e., vibrational- and rotational-state-dependent) but symmetric rotor description. The usual rotational quantum numbers are thus replaced with a single body-fixed azimuthal rotation quantum number, K, with various strategies introduced a posteriori to address rotor asymmetry. The new model fits the numerically computed rovibrational levels well, over a fairly broad range of vibrational (v) and rotational (J) excitations. The computed rotational constants agree well with previously reported experimental values [J. Chem. Phys. 58, 265 (1973)]. The explicitly v- and J-dependent approach used here should thus prove valuable in broader contexts—e.g., for an analysis of self-shielding in sulfur mass-independent fractionation, even though the rovibrational levels themselves exhibit mass-dependent fractionation.

The water-carbon monoxide dimer: new infrared spectra, ab initio rovibrational energy level calculations, and an interesting in-termolecular mode.

Bound state rovibrational energy level calculations using a high-level intermolecular potential surface are reported for H2O-CO and D2O-CO. They predict the ground K = 1 levels to lie about 20 (12) cm-1 above K = 0 for H2O-CO (D2O-CO) in good agreement with past experiments. But the first excited K = 1 levels are predicted to lie about 3 cm-1 below their K = 0 counterparts in both cases. Line strength calculations also indicate that mid-infrared transitions from the K = 0 ground state to this seemingly anomalous excited K = 1 state should be observable. These predictions are strikingly verified by new spectroscopic measurements covering the C-O stretch region around 2200 cm-1 for H2O-CO, D2O-CO, and HOD-CO, and the O-D stretch region around 2700 cm-1 for D2O-CO, HOD-CO, and DOH-CO. The experiments probe a pulsed supersonic slit jet expansion using tunable infrared quantum cascade laser or optical parametric oscillator sources. Discrete perturbations in the O-D stretch region give an experimental lower limit to the binding energy D0 of about 340 cm-1 for D2O-CO, as compared to our calculated value of 368 cm-1. Wavefunction plots are presented to help understand the intermolecular dynamics of H2O-CO. Coriolis interactions are invoked to explain the seemingly anomalous energies of the first excited K = 1 levels.

A determination of fundamental constants using HD+ ion and atomic hydrogen spectroscopy data

A determination of fundamental constants using HD+ ion spectroscopy data is discussed from comparisons between precision measurements and accurate theoretical predictions by taking into account recent measurements and updated CODATA values of the fundamental constants. The deuteron-proton mass ratio is determined with an uncertainty of 10-9. The ratio between the HD+ reduced mass and the electron mass is determined with an uncertainty of 7.3 × 10-10. The Rydberg constant, the proton-electron mass ratio and the deuteron-electron mass ratio are consistently determined with 10-9 , 10-6 , and 10-6 level uncertainties from an adjustment of the (v,L)=(0,0)→(0,1) and (v,L)=(0,2)→(8,3) HD+ ion transitions and of the (n,l,j,f)=1S1/2f=1→2S1/2f=1 atomic hydrogen transition. The result of the adjustment provides a test of the consistency of the two-body and three-body quantum electrodynamics energy level calculations for the atomic hydrogen and the HD+ ion.

Ambit: A programme for high-precision relativistic atomic structure calculations

We present the ambit software package for general atomic structure calculations. This software implements particle–hole configuration interaction with many-body perturbation theory (CI+MBPT) for fully relativistic calculations of atomic energy levels, electric- and magnetic-multipole transition matrix elements, g-factors and isotope shifts. New numerical methods and modern high-performance computing techniques employed by this software allow for the calculation of open-shell systems with many valence-electrons (N≥5) to a high degree of accuracy and in a highly computationally efficient manner. Program summaryProgram Title:ambitProgram Files doi:http://dx.doi.org/10.17632/7xfxhr9mg6.1Licensing provisions: GPLv3Programming language: C++11Nature of problem: Calculation of atomic/ionic spectra, including energy levels, electric and magnetic multipole transition matrix elements, and isotope shifts.Solution method: The programme calculates energy levels and wavefunctions using either configuration interaction (CI) only, or CI with many-body perturbation theory (CI+MBPT) in the Brillouin–Wigner MBPT formalism.Restrictions: The programme is not designed to treat highly-excited (Rydberg) states or continuum processes to a high degree of accuracy.Additional comments: Programme github repository

Calculating Energy Levels in 25Mg/25Al Mirror Nuclei


 
 
 
 Coulomb Displacement Energies in mirror nuclei 25Mg, 25Al have been calculated using shell model code OXBASH [1] and compared with experimental results. The code calculations were done in the USD model space with the W Hamiltonian [2]. The OXBASH code which is based on famous nuclear model, the shell model, deals with evaluating energy levels in nuclei. A comparison had been made between our results and the available experimental data [3] to test theoretical shell model description of nuclear structure in mirror nuclei. The energy states of mirror nuclei are almost identical, except for the small effects due to Coulomb interaction where the symmetry in being broken. Energy spectrum calculated with this code was in good agreement with the published experimental data [3].
 
 
 
 

The electronic structure of thorium monoxide: Ligand field assignment of states in the range 0-5 eV.

Configuration interaction ligand field theory (CI LFT) calculations of the electronic energy levels of ThO were performed by treating the molecular electronic states as Th 2+ free-ion levels perturbed by the ligand field of O2- . Twenty nine experimentally characterized ThO v = 0 energy levels, together with the energy difference between the v = 0 levels of the Y and W states were fitted using a CI LFT model that included Th 2+ 7s 2 , 6d7s, 6d2 , 7s7p, 6d7p, 5f7s, and 7p2 configurations. Predictions from these calculations were used to provide tentative assignments for 171 out of 250 ThO band heads listed by Gatterer et al. ["Molecular Spectra of Metallic Oxides", Specola Vaticana (1957)]. Term energies for 30 electronic states have been determined based on these assignments. Subsequently, the CI LFT model was refined by fitting to a set of 59 electronic term energies. The inclusion of CI effects together with integer valence, atomic-in-molecule, ionic bonding ideas reveals atomic energy level patterns that are multiply replicated in the molecular energy level patterns of six Th 2+ O2- atomic ion configurations (6d7s, 6d2 , 7s7p, 6d7p, 5f7s, and 7p2 ) revealing the underlying atomic ion structure that gives rise to the complex and seemingly erratic unassigned bands reported in the Vatican Atlas. © 2018 Wiley Periodicals, Inc.

Molecularly imprinted photoelectrochemical sensor for fumonisin B1 based on GO-CdS heterojunction

A rapid and ultrasensitive molecularly imprinted photoelectrochemical (MIP-PEC) sensing platform based on ITO electrode modified with GO-CdS heterojunction was prepared for ultrasensitive measure of fumonisin B1 (FB1). CdS quantum dots (QDs) were combined with a suitable amount of graphene oxide (GO) to form a heterojunction to enhance signal response with accurately calculating energy levels (VB/CB or HOMO/LUMO). The MIP-PEC sensor was successful fabricated after MIP was immobilized on the electrode with the basis of these results. In the phosphate buffer solution (PBS), it was clearly observed that the non-elution MIP-PEC sensor had almost no photocurrent response, which was due to the slower electron transfer speed. When the MIP-PEC sensor is eluted in ethanol, its photocurrent response was significantly restored, that was because the fact that the template molecules were washed away, and electron donors entered the holes and accelerated the electron transfer. Its photocurrent response was reduced because of holes blocked when the MIP-PEC sensor was hatched in the template molecules culture fluid. This phenomenon fully showed that the MIP-PEC sensor can specifically detect the target. Thus, The work has a linear range from 0.01 to 1000 ng mL−1 with a detection limit of 4.7 pg mL−1 for FB1. Furthermore, the fabricated MIP-PEC sensor will confirm the actual application.

A global potential energy surface for H3+

ABSTRACTA globally correct potential energy surface (PES) for the molecular ion is presented. The Born-Oppenheimer (BO) ab initio grid points of Pavanello et al. [J. Chem. Phys. 136, 184303 (2012)] are refitted as BOPES75K, which reproduces the energies below dissociation with a root mean square deviation of 0.05 cm−1; points between dissociation and 75,000 cm−1 are reproduced with the average accuracy of a few wavenumbers. The new PES75K+ potential combines BOPES75K with adiabatic, relativistic and quantum electrodynamics (QED) surfaces to provide the most accurate representation of the global potential to date, overcoming the limitations on previous high accuracy PESs near and above dissociation. PES75K+ can be used to provide predictions of bound rovibrational energy levels with an accuracy of approaching 0.1 cm−1. Calculation of rovibrational energy levels within PES75K+ suggests that the non-adiabatic correction remains a limiting factor. The PES is also constructed to give the correct asymptotic limit making it suitable for use in studies of the prototypical chemical reaction. An improved dissociation energy for is derived as cm−1.

The origin of carbon-related carrier compensation in p-type GaN layers grown by MOVPE

The role of carbon impurities in p-type GaN layers grown by metalorganic vapor phase epitaxy (MOVPE) was investigated. The lightly Mg-doped (∼1017 cm−3) p-type GaN samples with different carbon concentration [C] were prepared by controlling growth temperature and pressure. Temperature-dependent Hall-effect analyses exhibited an increase in donor concentration with increasing [C]. The low-temperature mobility also decreased with increasing [C], as a result of mobility limitation due to ionized impurity scattering. These results show that carbon atoms in MOVPE-grown p-GaN layers act as ionized donors and cause carrier compensation. Deep-level transient spectroscopy (DLTS) using bias pulses detected the existence of Hd traps (EV +0.88 eV) arising from the 0/−1 charge state of carbon on nitrogen sites (CN). The concentrations of Hd traps closely corresponded to [C] values in p-type GaN layers. Employing low-frequency capacitance DLTS to avoid carrier freeze-out at low temperatures, we newly discovered the Ha trap (EV +0.29 eV) whose concentration was directly proportional to the [C] value. These findings suggest that the Ha trap originates from CN identical to the Hd trap. Based on prior theoretical calculations of energy levels, the Ha trap can reasonably be assigned to a +1/0 donor state of CN. These results strongly suggest that a CN having two different charged states can compensate an electron and a hole in n-type and p-type GaN layers, respectively.