Calculation Of Energy Levels Research Articles

Radiative Rates and Electron Impact Excitation Rates for Transitions in He II

We report calculations of energy levels, radiative rates, collision strengths and effective collision strengths for transitions among the lowest 25 levels of the n ≤ 5 configurations of He II. The general-purpose relativistic atomic structure package (grasp) and Dirac atomic R-matrix code (darc) are adopted for the calculations. Radiative rates, oscillator strengths and line strengths are reported for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2) and magnetic quadrupole (M2) transitions among the 25 levels. Furthermore, collision strengths and effective collision strengths are listed for all 300 transitions among the above 25 levels over a wide energy (temperature) range up to 9 Ryd (10 5.4 K). Comparisons are made with earlier available results, and the accuracy of the data is assessed.

Precision calculation of energy levels for four-valent Si I

We report results of the calculation of the low-lying levels of neutral Si using a combination of the configuration interaction and many-body perturbation theory (CI+MBPT method). We treat Si I as an atom with four valence electrons and use two different starting approximations, namely $V^{N-2}$ and $V^{N-4}$. We conclude that both approximations provide comparable accuracy, on the level of 1%.

Energies, wavelengths, lifetimes, E1, M1, E2, and M2 transitions rates for the sulfur isoelectronic sequence Fe XI, Nb XXVI–In XXXIV

Energies, wavelengths, lifetimes, oscillator strengths, electric dipole (E1), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2) transition rates among the 42 fine structure levels belonging to the 3s23p4, 3s23p33d, and 3s3p5 configurations for S-like Fe and S-like ions with 41 ≤ Z ≤ 49 are calculated using the fully relativistic multiconfiguration Dirac–Fock (MCDF) method. In the calculations, contributions from correlations within the n = 6 complex, Breit interaction, and quantum electrodynamics effects are included. Detailed comparisons are made between the present results and the available experimental and other theoretical data. We found that our calculated energy levels generally agree within ≤0.5% with the experimentally compiled results, and the transition rates agree within ≤12% with other theoretical results for a majority of the transitions. These accurate theoretical data should be beneficial in fusion plasma research and astrophysical applications.

Persistent photoconductivity in ZnO nanowires: Influence of oxygen and argon ambient

ZnO nanowires typically show persistent photoconductivity (PPC), which depends in their temporal behaviour on the ambient. We investigate ZnO nanowires in oxygen and argon ambient and analyze the PPC both on the short and on the long time scale to sort out the underlying mechanisms. Wavelength dependent excitation shows the energy barrier for the PPC to be around 150 meV below the band gap of ZnO, independent of the ambient atmosphere. In photocurrent measurements at constant wavelength, a log-logistic dependence of the conductivity on the partial oxygen pressure is observed. The experimental results are compared to a model of Bonasewicz et al. [J. Electrochem. Soc. 133, 2270 (1986)] and can be explained by oxygen adsorption processes occurring on the surface of the ZnO nanowires. From temperature dependent measurements of the decay times in oxygen and argon ambient, the related activation energies for the fast and slow decay processes are determined. Comparing our results to theoretical calculations of energy levels of intrinsic defects [Janotti and Van de Walle, Phys. Status Solidi B 248, 799 (2011)], we find oxygen vacancies to be related to the fast decay processes, whereas adsorption and desorption processes of oxygen on the ZnO nanowire surface account for the slow part.

Extended calculations of energy levels, radiative properties, AJ, BJ hyperfine interaction constants, and Landé gJ-factors for oxygen-like Kr XXIX

Using the multiconfiguration Dirac–Fock method and the second–order many–body perturbation theory method, highly accurate calculations are performed for the lowest 344 fine-structure levels arising from the 2s22p4, 2s22p5, 2p6, 2s22p33s, 2s22p33p, 2s22p33d, 2s22p43s, 2s22p43p, 2s22p43d, 2p53s, 2p53p, 2p53d, 2s22p34s, 2s22p34p, 2s22p34d, 2s22p34f, and 2s2p44s configurations in O-like Kr XXIX. Complete and consistent atomic data, including excitation energies, lifetimes, wavelengths, hyperfine structures, Landé gJ-factors, and E1, M1, E2, M2 transition rates, line strengths, and oscillator strengths among these 344 levels are obtained. Comparisons are made between our two different sets of results, as well as with the other available experimental and theoretical values. For O-like Kr only a few levels have been experimentally established. The accuracy of our calculated energies is however high enough to facilitate identifications of observed lines involving the n=3,4 levels. The calculated data are also useful for modeling and diagnosing fusion plasmas.

Energy levels, lifetimes and radiative data of W LV

Calculations of energy levels, radiative data and lifetimes are reported for tungsten Ca-like ion (W LV) by using multi-configuration Dirac–Fock (MCDF) method. The GRASP2K package is adopted to carry out a large-scale systematic computation with a restricted active space treatment; the Breit interaction and QED effects are included in subsequent relativistic configuration interaction calculations. The energies and lifetimes of the lowest 119 levels are listed; the main leading configuration of the levels is of the ground state configuration [Ne]3s23p63d2 and the first excited configuration [Ne]3s23p53d3. The wavelengths, radiative rates and oscillator strengths for relatively strong E1, E2, M1, and M2 transitions are listed. Comparisons with earlier experimental and theoretical values are made. The average relative deviations of energy levels from the NIST results and E1 transition wavelengths from the EBIT experimental results have turned to be only 0.20% and 0.13%, respectively. The other present results are in reasonable agreement with available data. These agreements confirm the reliability and accuracy of the current results. The present datasets may help us with the investigation of the electron–electron correlation effects in complex multi-electron highly charged heavy ions and of the diagnosis of tungsten impurity plasmas in fusion science.

Wavelengths, transition probabilities, and oscillator strengths for M-shell transitions in tungsten ions with partially filled 3p subshell

Wavelengths, transition probabilities, and oscillator strengths have been calculated for M-shell electric dipole (E1) transitions in Al-like W61+ through Cl-like W57+, with partially filled 3p subshell. The fully relativistic multiconfiguration Dirac–Fock (MCDF) method, taking quantum electrodynamical effect and Breit correction into account, was used in the calculations. Calculated energy levels of M-shell excited states in Al-like through Cl-like W ions from the method were compared with some available theoretical and experimental results, and good agreement with them was achieved.

35,37,39S isotopes in sd–pf space: Shell-model interpretation

The structure of 35,37,39S isotopes is described by performing comprehensive shell model calculations with SDPF-U and SDPFMW interactions. Protons and neutrons are restricted to the sd-shell for N<20, neutrons start to fill the pf-shell for N>20. Natural parity states are described by only in-shell mixing, unnatural parity states with 1p–1h inter-shell neutron excitations. With SDPF-U interaction, reported are the results for natural parity states only because this interaction is not suitable for cross shell excitations. Calculated energy levels, electromagnetic properties and spectroscopic factors are in good agreement with the recently available experimental data.

Synthesis and photostability of 1,4-bis(5-phenyloxazol-2-yl)benzene (POPOP) structural isomers and their trimethylsilyl derivatives

In this work, a versatile synthetic method for preparation of linear phenyloxazoles and their organosilicon derivatives under mild conditions via a combination of van Leusen and direct CH arylation reactions is reported. It was used for the synthesis of a novel trimethylsilyl (TMS) derivative of blue laser dye 1,4-bis(5-phenyloxazol-2-yl)benzene (POPOP) and its structural isomer 1,4-bis(2-phenyloxazol-5-yl)benzene (isoPOPOP) with and without TMS substituents. All of the compounds demonstrated high photoluminescence quantum yields and large molar extinction coefficients, which further increased for their TMS derivatives. Measurements of accelerated photodegradation of the dyes in diluted THF solutions revealed that POPOP-type compounds are twice more stable than their isoPOPOP-type isomers, independent of the presence or absence of TMS substituents. Cyclic voltammetry (CV) investigations revealed that POPOP-type dyes are more electrochemically stable as compared to their isoPOPOP-type isomers. Quantum chemical TD DFT calculations of the frontier energy levels of the dyes were in a good agreement with the experimental data obtained by CV. Single-crystal X-ray diffraction experiments revealed significant structural differences between crystal lattices of the dyes. Due to facile synthesis and excellent optical properties as well as high photo- and thermo- stability the novel luminescent dyes may find wide application in organic photonics.

Energy Levels Calculations of 24 Al and 25 Al Isotopes

In this article, the energy levels of Aluminum isotopes 24Al and 25Al are calculated using OXBASH shell model code. The calculations were carried out in the SD model space with the W and CW Hamiltonian [1, 2] using the code OXBASH for windows PC [3]. This code which is based on one of the most applicable nuclear models, the shell model, deals with evaluating energy levels in nuclei. Using this code to calculate the energy levels of an isotope, produces several files that contains a set of data. The ground state energy of a nucleus and also the probable energies of excitation levels can be calculated by OXBASH. Programs will be reliable only when results meet experimental procedures. A compilation of SD-shell energy levels calculated with the USD Hamiltonian was published around 1988. A comparison had been made between our results and the available experimental data to test theoretical shell model description of nuclear structure in Aluminum isotopes. The calculated energy spectrum is in good agreement with the available experimental data.

Applying a Smolyak collocation method to Cl2CO

ABSTRACTPhosgene (Cl2C=O) is extremely poisonous, underscoring the importance of accurate infrared detection. Here, the computed vibrational energy levels of phosgene are reported for the first time from a six-dimensional potential energy surface (PES) that was constructed from 25,000 single-point energy computations at the CCSD(T)/cc-pVTZ level of theory. The computed points were fit using a neural network method, and the resulting PES was employed in the determination of vibrational energies and wavefunctions. Bond coordinates were utilised in conjunction with a collocation method to minimise problems that arise from the complicated nature of the kinetic energy operator. The collocation method makes possible the computation of energy levels without integral evaluation, and without the need to solve a generalised eigenvalue problem. Moreover, it is built on a nondirect product-pruned basis that is much smaller than the direct product basis that would be required to obtain the same accuracy.

Configuration interaction calculations and excitation rates of X-ray and EUV transitions in sulfurlike manganese

Fine-structure calculations of energies and transition parameters have been performed using the configuration interaction technique (CI) as implemented in CIV3 code for sulfurlike manganese, Mn X. The calculations are executed in an intermediate coupling scheme using the Breit-Pauli Hamiltonian. As well as, energy levels and oscillator strengths are calculated using LANL code, where the calculations by LANL have been used to estimate the accuracy of the present CI calculations. The calculated energy levels, oscillator strengths, and lifetimes are in reasonable agreement with the published experimental and theoretical values. Electron impact excitation rates of the transitions emit soft X-ray and extreme ultraviolet (EUV) wavelengths have been evaluated. The level population densities are calculated using the collisional radiative model (CRM), as well. The collisional excitation rates and collision strengths have been calculated in the electron temperature range ≤ the ionization potential, ∼1–250eV.

The Evolution of 146Nd– 156Nd Isotope States under the Framework of BM, IBM-1, IVBM and D-G

The properties of the ground, beta and negative parity state bands of 146Nd–156Nd isotopes have been studied. The ratio of gamma energy over spin has been calculated and drawn as a function of spin (I) to show the ground-state evolution for each isotope. The ratio between the excitation energies of successive (I+2) and (I) states as a function of spin (I) has been calculated and drawn to determine the property of the ground-state bands of 146Nd–156Nd isotopes. The odd-even staggering has been drawn to determine the energy difference of the states of the ground-state bands and the negative-parity bands. The energy levels for the ground-state band of 146Nd–156Nd have been calculated using the Bohr-Mottelson Model, the Interacting Boson Model, the Interacting Vector Boson Model and the Doma–El-Gendy Relation. The energy levels of the beta band for the measured experimentally levels of 148Nd, 150Nd and 152Nd have been calculated using the Interacting Boson Model. The energy levels of the negative parity band of the 146Nd, 148Nd, 150Nd, 152Nd and 156Nd isotopes have also been calculated using the Bohr-Mottelson Model and the Interacting Vector Boson Model. The calculated energy levels compared with the experimental data indicate the quality of the fit presented in this paper.

Calculation of levels, transition rates, and lifetimes for the arsenic isoelectronic sequence Sn XVIII-Ba XXIV, W XLII

Multi-configuration Dirac–Fock (MCDF) calculations of energy levels, wavelengths, oscillator strengths, lifetimes, and electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), magnetic quadrupole (M2) transition rates are reported for the arsenic isoelectronic sequence Sn XVIII-Ba XXIV, W XLII. Results are presented among the 86 levels of the 4s24p3, 4s4p4, 4p5, 4s24p24d, and 4s4p34d configurations in each ion. The relativistic atomic structure package GRASP2K is adopted for the calculations, in which the contributions from the correlations within the n≤7 complexes, Breit interaction (BI) and quantum electrodynamics (QED) effects are taking into account. The many-body perturbation theory (MBPT) method is also employed as an independent calculation for comparison purposes, taking W XLII as an example. Calculated results are compared with data from other calculations and the observed values from the Atomic Spectra Database (ASD) of the National Institute of Standards and Technology (NIST). Good agreements are obtained. i.e, the accuracy of our energy levels is assessed to be better than 0.6%. These accurate theoretical data should be useful for diagnostics of hot plasmas in fusion devices.

3-Cyano-2-azaanthracene-based “push-pull” fluorophores: A one-step preparation from 5-cyano-1,2,4-triazines and 2,3-dehydronaphthalene, generated in situ

A facile one-step approach towards 3-cyano-2-azaanthracenes via the [4+2] cycloaddition reaction between 5-cyano-1,2,4-triazines and 2,3-dehydronaphthalene, generated in situ from commercially available 3-amino-2-naphthoic acid, has been reported. The influence of the 1,2,4-triazine ring substituents nature on the product yield has been studied. The observed experimental results were confirmed by DFT calculations of the HOMO-LUMO energy levels of the both cycloaddends. The photophysical properties of the products have been investigated.

Calculation of Level Density Parameter of Nuclear Reaction Using Neural Network

Level density parameter (LDP) calculation is dependent upon shell correction value, which usually is obtained by using Strutinsky method. The Strutinsky method is method that uses energy levels from certain potential as main input. Therefore for each mass number it strongly needs the energy levels calculation. The energy levels computation is time-consuming process; hence, the new application of computation technique is needed to reduce computation time. This paper explains the application of neural network in LDP calculation. Based on knowledge from box type and harmonic potentials, LDP is predicted by using arbitrary potential

Energies and radiative transitions (E1, E2, and M1) for hydrogen-like thorium

Hydrogen-like ions with high Z present unique opportunities to promote the understanding of atomic structure. On the other hand, determining the atomic structure of hydrogen-like atoms provides us the test of relativistic effects as well as accurate values of the spectral characteristics required for many applications. For this reason we have calculated level energies of hydrogen like thorium (Th89+, Z = 90) with both multiconfiguration Hartree–Fock (MCHF) and multiconfiguration Dirac–Fock (MCDF) methods. These calculations have contained the Breit–Pauli relativistic corrections in MCHF calculation and quantum electrodynamics effects in MCDF calculations besides electron correlations. The wavelengths, λ, weighted oscillator strengths, gf-value, and transition probabilities, Aki, have been also represented for allowed (E1) and forbidden (E2 and M1) transitions. We have compared our results with only theoretical work results because there is no available experimental data for Th89+.

All-order calculations of the spectra of superheavy elements 113 and 114

We apply a recently developed method (V. A. Dzuba, PRA 90, 012517 (2014); J. S. M. Ginges and V. A. Dzuba, PRA 91, 042505 (2015)) to calculate energy levels of superheavy elements Uut (Z = 113), Fl (Z = 114), and Fl+. The method combines the linearized single-double coupledcluster technigue, the all-order correlation potential method and configuration interaction method. Breit and quantum electrodynamic corrections are included. The role of relativistic and correlation effects is discussed. Similar calculations for Tl, Pb and Pb+ are used to gauge the accuracy of the calculations.

Understanding the light-emitting mechanism of an X-shape organic thermally activated delayed fluorescence molecule: First-principles study

The light-emitting mechanism of an X-shape organic thermally activated delayed fluorescent molecule is investigated based on first-principles calculations. It is found that there are two stable configurations for the ACRSA molecule, and that the molecule with conformer A is nonluminous. Further, the excited states dynamics of conformer B is studied. The normal modes analysis of the reorganization energy indicates that the non-radiation process of the first singlet excited state (S1) mainly comes from the out-of-plane vibration with low frequencies. Besides, calculations of energy levels of excited states demonstrate that the up-conversion happens between the S1 and T1 states.

EXTENDED RELATIVISTIC CONFIGURATION INTERACTION AND MANY-BODY PERTURBATION CALCULATIONS OF SPECTROSCOPIC DATA FOR THE N ≤ 6 CONFIGURATIONS IN Ne-LIKE IONS BETWEEN Cr xv AND Kr xxvii

ABSTRACT Level energies, wavelengths, electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transition rates, oscillator strengths, and line strengths from combined relativistic configuration interaction and many-body perturbation calculations are reported for the 201 fine-structure states of the , , , , , , and configurations in all Ne-like ions between Cr xv and Kr xxvii. Calculated level energies and transition data are compared with experiments from the National Institute of Standards and Technology (NIST) and CHIANTI databases, and other recent benchmark calculations. The mean energy difference with the NIST experiments is only 0.05%. The present calculations significantly increase the amount of accurate spectroscopic data for the n &gt; 3 states in a number of Ne-like ions of astrophysical interest. A complete data set should be helpful for analyzing new observations from solar and other astrophysical sources, and is also likely to be useful for modeling and diagnosing a variety of plasmas, including astronomical and fusion plasma.