Non-relativistic Configuration Research Articles

The lowest electronic states of Ne2 +, Ar2 + and Kr2 +: comparison of theory and experiment

Non-relativistic configuration interaction (CI) ab initio calculations using large basis sets have been carried out to determine the potential curves of the first electronic states of Ne2 +, Ar2 + and Kr2 +. The spin—orbit interaction was treated assuming that the spin—orbit coupling constant is independent of the internuclear separation (R). For Ar2 +, calculated dissociation energies and equilibrium separations are in good agreement with experimental results. The calculations for Ne2 + suggest that the lowest vibrational level of the I(1/2u) ground state observed by threshold photoelectron spectroscopy by Hall et al. [1995, J. Phys. B: At. molec. opt. Phys., 28, 2435] and assigned to either ν = 0 or ν = 2 actually corresponds to ν = 4. The calculations also predict the I(1/2g) state of Ne2 + and Ar2 + to possess a double-well potential and that of Kr2 + to be repulsive at short range and to only possess a single shallow well at large internuclear separation. The ab initio calculations provide an explanation for the observation made by Yoshii et al. [2002, J. chem. Phys., 117, 1517] that Kr2 + and Xe2 + dissociate after photoemission from the II(1/2u) state to the I(1/2g) state whereas Ar2 + does not.

Model comparisons for high-Z non-LTE steady-state calculations

Advances in computer technology and code development have made it possible to perform plasma kinetics calculations based on high- Z atomic structure corresponding to different levels of detail. Various atomic models have been implemented in the Los Alamos suite of codes in recent years for performing detailed non-equilibrium kinetics calculations. These include non-relativistic configuration average models with unresolved transition arrays (UTA), detailed fine structure models including configuration interaction and intermediate coupling that are capable of achieving spectroscopic accuracy for low- Z plasmas, and fully relativistic configuration average models employing the concept of the unresolved transition array, UTA, for modeling high- Z plasmas. Fully relativistic fine structure calculations have also been implemented and used primarily for accuracy checks. In addition, the fractional occupation number method has been introduced in the relativistic structure code to reduce computational times without reducing data quality. Finally, we will discuss a method that has been developed to use the populations extracted from a non-relativistic kinetics calculation in a relativistic spectral simulation. The purpose of the present work is to compare the emission spectra predicted by the various models and methods using consistent sets of atomic electron configurations and cross-sections for a gold plasma.

A consistent approach in relativistic random phase approximation

The fine structure of the IsoVector Giant Dipole Resonance (IVGDR) in the doubly-magic nuclei 40,48Ca observed in inelastic proton scattering experiments under 0∘ is used to investigate the role of different mechanisms contributing to the IVGDR decay width. Characteristic energy scales are extracted from the fine structure by means of wavelet analysis. The experimental scales are compared to different theoretical approaches allowing for the inclusion of complex configurations beyond the mean-field level. Calculations are performed in the framework of RPA and beyond-RPA in a relativistic approach based on an effective meson-exchange interaction, with the UCOM effective interaction and, for the first time, with realistic two- plus three-nucleon interactions from chiral effective field theory employing the in-medium similarity renormalization group. All models highlight the role of Landau fragmentation for the damping of the IVGDR, while the differences in the coupling strength between one particle-one hole (1p-1h) and two particle-two hole (2p-2h) correlated (relativistic) and non-correlated (non-relativistic) configurations lead to very different pictures of the importance of the spreading width resulting in wavelet scales being a sensitive measure of their interplay. The relativistic approach with particle-vibration coupling, in particular, shows impressive agreement with the number and absolute values of the scales extracted from the experimental data.

Hyperfine structure of lithium-like ions

Abstract The hyperfine splitting values of the ground state of lithium-like ions are calculated in the range Z = 7–28. The calculations are based on a combination of the 1/Z perturbation theory and the nonrelativistic configuration interaction Hartree-Fock (CI-HF) method. The relativistic corrections are calculated in the zeroth and first orders in 1/Z. The nuclear charge and magnetization distribution corrections and the radiative corrections are taken into account. The uncertainty of the calculations is estimated to be in the range 0.06–0.15 percent.

Photoelectron spectroscopy of f-element organometallic complexes. 9. A comparative fully relativistic/nonrelativistic first-principles X.alpha.-DVM and photoelectron spectroscopic investigation of electronic structure in homologous 4f and 5f tris(.eta.5-cyclopentadienyl)metal(IV) alkoxide complexes

The electronic structure of ([eta][sup 5]-C[sub 5]H[sub 5])[sub 3]MOR (M = Ce, Th, U) complexes has been investigated by He I and He II UV photoelectron spectroscopy combined with SCF X[alpha]-DVM calculations. Fully relativistic Dirac-Slater calculations were also carried out for the M = Th complex. The nonrelativistic calculations indicate that metal-ligand interactions involving the highest energy ligand orbitals involve primarily metal 5f orbitals while 6d admixtures are found for lower energy orbitals. The M-O bonding is both [sigma] and [pi] in nature and involves primarily metal 6d atomic orbitals. Evidence of a charge redistribution mechanism along the CH[sub 3][yields]O[yields]M[yields]Cp[sub 3] direction provides a satisfactory explanation for the shortened M-O distances and strong propensity for nearly linear M-O-CH[sub 3] linkages observed in diffraction studies. The fully relativistic calculations show that metal d contributions are slightly underestimated at the nonrelativistic level. Such deviations do not, however, alter the overall description of the metal-ligand bonding. The nonrelativistic configuration of the metal center compares well with the relativistic data. Gas-phase ionization energies can be accurately and comparably evaluated at the computationally more efficient nonrelativistic level if optimized basis sets and potential representations are used.

Improved calculation of fine-structure splittings in the ground state of potassiumlike ions

The fine-structure splitting between the 3p63d2DJ, J = 3/2 and J = 5/2 levels of K-like ions, Ti3+ to U73+, are calculated by means of Dirac–Fock single-configuration and multiconfiguration wave functions. The multi-configuration calculation includes jj configurations arising from some selected nonrelativistic configurations in the M-shell Coulomb complex; these include all the Dirac–Fock configurations with the principal quantum number n = 3, which are degenerate in the pure jj coupling limit for infinite nuclear charge Z, along with other configurations such that the calculated energy is correct to order Z2 and Z asymptotically. The difference between known experimental and calculated multiconfiguration Dirac–Fock fine-structure splittings is almost independent of Z, thus allowing us to predict unknown values reliably. From this plot and a comparison of theoretical and experimental results we conclude that the observed fine-structure splitting of Ag28+ [ J. Opt. Soc. Am. B2, 1661 ( 1985)] is too small. We present splittings in high-Z K-like ions for which experimental values are unknown.

Anomalous high gold-metal bond stabilities: Relativistic configuration-interaction calculations for AuLa and AuLu.

Gold-metal dissociation energies measured by mass-spectroscopic methods in 1967 by Gingerich and co-workers showed unexpectedly high ${\mathit{D}}_{\mathit{e}}$ values compared with those of the corresponding copper and silver compounds. In the past, this has been explained in terms of the increased ionicity of the diatomic gold compounds on the basis of the Pauling model. In fact, the very high dissociation energies observed for AuLa and AuLu arise from relativistic effects, as shown by calculations of nonrelativistic and relativistic configuration interactions. The expected overall trend in the group-11 series is also explained (bond stabilities: AuM\ensuremath{\gg}CuM>AgM, M any metal atom) in terms of relativistic effects and new spectroscopic data are given for AuLa and AuLu.

Multiconfiguration Dirac-Fock calculation of the forbidden M1 transitions in the beryllium isoelectronic sequence

Calculations of the magnetic dipole M1 transition rates between 3P0 to 3P1 and 3P1 to 3P2 levels of 1s22s2p configuration in the beryllium isoelectronic sequence have been performed using the multiconfigurational Dirac-Fock extended average level (MCDF-EAL) method. Three nonrelativistic configurations 1s22s2, 1s22p2 and 1s22s2p are used. Breit and QED effects are treated as first-order perturbations. The role of the relativistic effects is crucial for the calculation of these transition rates. The transition rates between the magnetic fine-structure levels show a screened scaling behaviour. Experimental data are not available for comparison with the results.

Relativistic all-electron configuration interaction calculations on the gold atom

We present the results of relativistic and non-relativistic self-consistent field and configuration interaction calculations for the gold atom, using the spin-free no-pair Hamiltonian in a basis set expansion. A new basis set for the gold atom is discussed and its results in relativistic and non-relativistic self-consistent field calculations are compared to those of numerical Dirac-Hartree-Focic and Hartree-Fock calculations, respectively. Excitation energies, electron affinities and ionization potentials were calculated using a multi-reference configuration interaction technique and are in reasonable agreement with experiment in the relativistic case.

Ab initio calculations on the ground and excited electronic states of KrH

Non-relativistic configuration interaction calculations have been carried out on the ground and excited electronic states of KrH. The results show that the ground state is repulsive, except for a van der Waals minimum at large R. The excited states are bound with minima at R near the equilibrium bond length of KrH + and have Rydberg character. The theoretical values for the rotational constants and also for T 0 of the 3 2Σ + (p)→A 2Σ + (s) transition are in good agreement with the corresponding experimental values. Calculations on the vertical transition energies indicate that the 8141 Å band of KrH should be assigned to the 2 2Π→A 2Σ + transition.

Density and density matrix from optimized linearly independent product basis functions for Be

The density matrix was computed from the density using basis orbitals which form linearly independent products (LIP). Calculations were performed on the Be atom using LIP bases containing several of the natural spin orbitals from an accurate nonrelativistic 650-term configuration interaction (CI) wavefunction. Calculations were also performed using a basis set of 6 s-type orbitals optimized so that the lowest eigenvalue, d1, of the overlap matrix of products is maximized and the energy of a small CI wavefunction is minimized. The value of d1 in the optimized basis is 1 × 10−7. The density and the potential energy obtained from the 650-term CI wavefunction were accurately reproduced by the density matrix expressed in the optimized LIP basis, but the kinetic energy was somewhat less accurate.

X-ray emission spectra from laser-produced cobalt plasma

Based on theoretical calculations by our non-relativistic configuration interaction computer code, we have successfully identified the x-ray spectra from the cobalt plasma produced by high-power laser. Here we focus on the spectra consisting of x-ray line emission from the N-like and C-like ions. Many new x-ray lines have been identified.

Relativistic SCF calculations of transitions in the principal and intercombination series of mercury

Relativistic self-consistent-field (SCF) calculations of oscillator strengths, excitation energies and singlet-triplet splittings are reported for the 6 s 2 1 S 0-6 snp 3 P 1, 1 P 1 transitions in mercury with 6 ⩽ n ⩽20. Intermediate coupling is assumed for excited 3 P 1, 1 P 1 states, and for the ground 6 1 S 0 state additional 6 p 2 1 2 , 6 p 2 3 2 configurations are admixed to account for much of the ground-state intravalence correlation. The core-valence correlation is included within the core-polarization approximation. We show that theoretical explanations of the intensity anomaly at high n, which are based on intermediate coupling, require that calculations performed in the optimized level (OL) scheme include effects which affect the 3 P 1 and 1 P 1 states separately. These calculations cannot explain the anomaly because of extremely strong cancellation in the radial integrals for the 6 1 S 0- n 3 P 1 transitions. The calculations suggest that intermediate coupling is not the only factor responsible for the observed intensity anomaly, and we expect other correlation effects (represented by the mixing of different non-relativistic configurations) to play an even more important role. In the frozen-core approximation used in our SCF calculations, fairly reliable excitation energies and singlet-triplet splittings are obtained simultaneously with the oscillator strengths, provided the Hg +-like frozen core is used rather than the core frozen in the 6 1 S 0 ground state.

NON- RELATIVISTIC AND RELATIVISTIC ATOMIC CONFIGURATION INTERACTION THEORY EXCITATION ENERGY AND RADIATIVE TRANSITION PROBABILITY

We have established the non-relativistic and relativistic atomic configuration interaction methods to calculate excitation energies of low excited states as well as radiative transition probabilities for allowed and forbidden transitions. In order to check our computer codes, we have calculated the excitation energies for N=2 states and the corresponding radiative transition rates for the atomic helium. The results of our non-relativistic and relativistic calculations agree with each other. The excitation energies are accurate within a few thousandths, the corresponding radiative transition probabilities within a few percents. Our methods can be readily applied to other atoms as well as ionized atoms.

Electron impact excitation of forbidden transitions in MG VII

view Abstract Citations (17) References (30) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Electron impact excitation of forbidden transitions in MG VII Aggarwal, K. M. Abstract The R-matrix approach has been applied to the electron impact excitation of forbidden transitions among the 1s2 2s2 2p2, 1s2 2s 2p3, and 1s2 2p4 configurations of Mg VII, using the nonrelativistic configuration interaction wave functions to compute the electron collision strengths. These strengths show a complex resonance structure over the entire threshold energy region. The entire collision strength spectrum has been averaged over a Maxwellian distribution of electron velocities to get the effective collision strengths, from which the excitation and deexitation rate coefficients are easily obtainable. The results are listed at a series of electron temperatures below 500,000 K, which are suitable for astrophysical applications. Publication: The Astrophysical Journal Supplement Series Pub Date: November 1984 DOI: 10.1086/190986 Bibcode: 1984ApJS...56..303A Keywords: Atomic Excitations; Configuration Interaction; Electron Impact; Forbidden Transitions; Magnesium; Transition Probabilities; Astrophysics; Cosmic Plasma; Electron Energy; Electron Scattering; Least Squares Method; Maxwell-Boltzmann Density Function; Plasma Density; Plasma Temperature; Wave Functions; Astrophysics full text sources ADS |

Relativistic and non-relativistic configuration interaction calculations for atoms having a closed core and two valence spin-orbitals

To describe the incidence, etiological factors, functional impairment and therapeutic management of scapular fractures after reverse shoulder arthroplasty (RSA) in rotator cuff arthropathy.A retrospective study was conducted on 126 RSA between 2009 and 2011, in which four fractures were identified that were compared with a control group of 40 patients. An analysis was performed on the variables related to the surgical technique, functional results, and quality of life (Constant scale, EQ-5D).The fracture incidence was 3.28% with a mean age of 74.7 years. The mean time until diagnosis was 11.9 months.The preoperative Constant score in the control group was 37.3%, and 34.7% in the fracture group (P > .05); postoperative Constant score: 81.2 and 66.5%, respectively (P > .001). Forward elevation and abduction in fracture patients decreased by 39° (P = .02), and 34° (P = .057) respectively. The perceived quality of life (EQ-VAS) was lower in the fracture group (60 vs. 76) (P = .002).There were no instability cases, and no revision surgery was required. The union rate was 50% after a mean follow-up 39.6 months.Scapular fracture after RSA is a rare complication. Despite its presence, the functional outcomes and quality of life of these patients are higher than preoperatively; however, they are lower than that obtained in patients with RSA without this complication. More prospective studies are needed to define guidelines for therapeutic action against this complication.Describir la incidencia, factores etiológicos, repercusión funcional y actitud terapéutica de las fracturas de acromion y espina de la escápula tras artroplastia invertida por artropatía de manguito rotador.Análisis retrospectivo de 126 artroplastias inversas entre los años 2009–2011. Se identificaron 4 fracturas que se compararon con un grupo control de 40 pacientes. Se analizan variables relacionadas con el proceso quirúrgico, funcionales y de calidad de vida (escala Constant, EQ-5D).La incidencia de la fractura fue 3,28% (4 pacientes), edad media 74,7 años y tiempo medio hasta el diagnóstico 11,9 meses.El Constant preoperatorio del grupo control fue de 37,3% y de los pacientes con fractura 34,7% (p > 0,05); el postoperatorio 81,2% y 66,5%, respectivamente (p < 0,001). La anteversión y abducción en los pacientes con fractura descendieron en 39° (p = 0,02) y 34° (p = 0,057) respectivamente con respecto al grupo control. La calidad de vida percibida (EQ-VAS) es inferior en el grupo de fractura (60 vs 76) (p = 0,002).En ninguno de los casos de fractura se observó inestabilidad, no precisando cirugías de revisión. La tasa de consolidación fue de un 50% tras un seguimiento medio de 39,6 meses.La fractura de escápula tras artroplastia invertida es una complicación poco frecuente. A pesar de su aparición los resultados funcionales y de calidad de vida de estos pacientes son superiores a los presentes preoperatoriamente, sin embargo, resultan inferiores a los de los pacientes intervenidos en los que no se encuentra dicha complicación. Son necesarios más estudios prospectivos que nos ayuden a definir las pautas de actuación terapéutica ante esta complicación.

Ab initio studies of electron correlation in rare-earth ions. I. Intrashell correlation for 4f2in Pr3+

The effect of electron correlation on the energies of the LS states determined by the 4f2 electronic shell is studied for the Pr3+ ion by means of a non-relativistic configuration interaction method. The excited orbital set included orbitals of s, p, d, f, g and h symmetry. To speed up the convergence and to reduce the impact of the virtual excitations to the continuum, the radial functions in these orbitals were partially optimised in a series of MCHF calculations. It is shown that the 4f5f configurations are dominant in the description of intrashell correlation effects for the 4f2 shell. The inclusion of these correlation effects also resulted in a considerable improvement of the theoretical multiplet splittings over the HF results. However, intershell correlation effects have to be taken into account to get satisfactory agreement.

Coupling constants and the nonrelativistic quark model with charmonium potential

Hadronic coupling constants of the vertices including charm mesons are calculated in a nonrelativistic quark model. The wave functions of the mesons which enter the corresponding overlap integrals are obtained from the charmonium picture as quark-anti-quark bound state solutions of the Schrödinger equation. The model for the vertices takes into account in a dynamical way the SU 4 breakings through different masses of quarks and different wave functions in the overlap integrals. All hadronic vertices involving scalar, pseudoscalar, vector, pseudovector and tensor mesons are calculated up to an overall normalization constant. Regularities among the couplings of mesons and their radial excitations are observed: (i) Couplings decrease with increasing order of radial excitations; (ii) in general they change sign if a particle is replaced by its next radial excitation. The k-dependence of the vertices is studied. This has potential importance in explaining the unorthodox ratios in different decay channels (e.g. D D, D D ∗, D ∗ D ∗ ). Having got the hadronic couplings radiative transitions are obtained with the current coupled to mesons and their recurrences. The resulting width values are smaller than those conventionally obtained in the native quark model. The whole picture is only adequate for nonrelativistic configurations, as for the members of the charmonium- or of the γ-family and most calculations have been done for transitions among charmed states. To see how far nonrelativistic concepts can be applied, couplings of light mesons are also considered.

Nonrelativistic configuration interaction calculations for the ground state of the vanadium atom

A new scheme for constructing L2, Lz, S2, Sz eigenfunctions within the Hartree–Fock interacting subspace has been used to generate a first-order configuration-interaction wavefunction for the ground 4F state of the vanadium atom in the nonrelativistic approximation. The basis set consisted of 62 Slater-type orbitals, with l up to 5, transformed to Hartree–Fock orbitals in the ’’occupied’’ subspace and to pseudonatural orbitals in the ’’virtual’’ subspace. Approximately 70% of the correlation energy was recovered with 500 configurations (1023 terms formed from 31 496 Slater determinants). The charge density, momentum density, x-ray scattering factor, and Compton profile were computed from both the CI and SCF wavefunctions.

Relativistic and non-relativistic configuration interaction calculations for atoms having a closed core and two valence spin-orbitals

Relativistic and non-relativistic configuration interaction calculations for atoms having a closed core and two valence spin-orbitals