C. Froese Fischer

Breit-Pauli energy levels and transition rates for nitrogen-like and oxygen-like sequences

Breit-Pauli results for energy levels, lifetimes, and Lande gj factors have been determined for all levels up to 2p 2 3d of the nitrogen-like sequence (Z = 7-17) and 2p 3 3d of the oxygen-like sequence (Z = 8-20). Exceptions are some lower members of the sequence where the spectrum included only those levels below the second 2p 2 4s term in the case of N-like or 2p 3 4s in the case of O-like. The computed energy and E1, E2, Ml, M2 transition data between all levels, including convergence of the LS line strength for both length and velocity forms, may be viewed at a website. In this paper, critically evaluated transition data is presented for N I, O II, Mg VI, and Si VIII (N-like sequence) and O I, Ne III, Mg V, and Si VII (O-like) for E1 transitions including uncertainty estimates. The accuracy of energy levels is determined by comparison with experiment. Transition rates with uncertainties are compared with experiment and other theory.

Breit-Pauli energy levels, lifetimes, and transition data: beryllium-like spectra

Breit-Pauli results for energy levels, lifetimes, and some transition data are reported for all levels of the 2s2, 2s2p, 2p2, 2s3s, 2s3p, and 2s3d configurations of the Be-like spectrum for 4 Z12. A simultaneous optimization scheme was applied so that a radial basis could be determined for a set of terms that mix in the Breit-Pauli approximation. Convergence of the LS line strength is used as a factor in estimating accuracy as well as the agreement of energy levels and their splitting between theory and experiment. The results are evaluated by comparison with other theoretical results and experiment for transition rates.

RELCI: A program for relativistic configuration interaction calculations☆

Apparatus for cleaning/deburring manufactured parts, each part having an established axis of rotation, includes a conveyor operable to convey the parts in succession in intermittent step-by-step movement to a cleaning/deburring station and a drying station. At each of the cleaning/deburring and drying stations the part is driven in high speed rotation about its axis by a part rotating device. At the cleaning/deburring station the rotating part is sprayed with high pressure fluid and at the drying station high velocity air is discharged tangentially against the rotating part to strip residual fluid from the part. The spray nozzle assembly can be stationary, or can take the form of a transversing assembly for reciprocating movement along the longitudinal length of the part. Additionally, the transversing assembly can include rotation of the nozzle assembly about an axis as the nozzles are reciprocated longitudinally. Alternatively, the spray nozzle assembly can take the form of a pantograph assembly allowing the spray nozzles to trace the contours of the surface of the part as it rotates at high speed.

REOS99: A revised program for transition probability calculations including relativistic, correlation, and relaxation effects

Abstract Recent years have seen an increasing demand on accurate transition probability calculations for open-shell atoms and ions. To facilitate such investigations, the program REOS [S. Fritzsche, C.F. Fischer, Comput. Phys. Commun. 99 (1997) 323] has been developed which includes the effects of relativity, correlation, and the rearrangement of the bound-state electron density within the framework of the multiconfiguration Dirac–Fock model. Often, however, very large wave function expansions are indeed needed to obtain sufficiently accurate results which cannot be handled by the original program. Shortcomes of this program concern in particular the demand on memory and CPU time as well as its tight binding to the IBM XL Fortran standard. To resolve these drawbacks we present here a revised version, REOS99, which has been developed in line with the ANSI standard Fortran 90/95. Care has been taken to exploit the advantages of this new standard and to improve the efficiency and portability of the program.

HFS92: A program for relativistic atomic hyperfine structure calculations

Abstract We describe a program for the computation of magnetic dipole and electric quadrupole diagonal ( A J , B J ) and off-diagonal ( A J , J −1 , B J , J −1 , B J , J −2 ) hyperfine interaction constants. Approximate atomic wavefunctions are assumed to be linear combinations of configuration state functions, which are, in turn, constructed from four-component spin-orbitals to be many-particle eigenfunctions of the parity and angular momentum operators.

JJGEN: A flexible program for generating lists of jj-coupled configuration state functions

The success of large scale relativistic multiconfiguration Dirac-Hartree-Fock calculations for atomic systems rely on judiciously chosen configuration expansions. Dependent on the atomic system as well as on the studied properties, various correlation effects need to be considered. Based on the active set approach, this program allows the user to generate general lists of j j-coupled configuration state functions to be used as input to the grasp2K multiconfiguration Dirac-Hartree-Fock package [P Jonsson, X. He, C. Froese Fischer, I.P. Grant, Comput. Phys. Comm. (2007), in press].

Multiconfiguration Hartree-Fock Breit-Pauli results for 2P1/2-2P3/2 transitions in the boron sequence

The multiconfiguration Hartree-Fock method has been extended to include relativistic effects in the Breit-Pauli approximation. Results for the 2p 2P1/2-2p2P3/2 energy separation and M1 and E2 transition rates are presented and compared with other theory.

Convergence studies of MCHF calculations for Be and Li

MCHF n-expansion procedures are applied to the Be and Li- 1s22s2 1S ground state. Up to n=5 all configuration states are included. From n=6 results, a pattern was observed for triple and quadruple excitations and this pattern was then applied to the higher n. Calculations were performed up to n=10. For Be, the extrapolated total energy of -14.667314 Hartree and the double ionization energy of 1.011796 Hartree agree well with the predicted exact non-relativistic energies. An ab initio value of the quantity related to the Be 2s2-Be+ 2s specific mass shift is reported for the first time. The electron affinity for Li is predicted to be 0.6176 eV. Both of these values are in excellent agreement with experiment.

Spline algorithms for the Hartree-Fock equation for the helium ground state

Spline algorithms are evaluated for the non-linear, integro-differential equation describing the Hartree-Fock approximation for the He 1s21S ground state. The error in the energy decreases as h2K−2, where h is a grid parameter and K is the order of the spline. It is shown that for higher order splines, the method is fast and accurate, and contrary to the conclusion reached by Altenberger-Siczek and Gilbert, that spline methods are suitable for SCF atomic structure calculations. Accuracy and timing studies are presented as well as comparisons with other accurate procedures.

REOS — A program for relaxed-orbital oscillator strength calculations

Abstract A spontaneous decay of an excited atomic state leads to a rearrangement of the spatial electron distribution in the atom. This redistribution concerns the entire electronic cloud and not only the active electron in an atomic transition. For many-electron atoms, rearrangement effects are naturally included if the electronic wavefunctions of the initial and final states are determined independently. The separate optimization of the atomic states, however, yields two sets of one-electron orbitals which are not orthogonal to each other. This incomplete orthogonality also influences the calculation of transition amplitudes since, additionally, many small contributions arise from the radial overlap of electrons of different subshells which have the same symmetry. In the framework of the GRASP92 atomic structure package we describe a program for the computation of oscillator strengths and Einstein A and B coefficients. The program is based on a determinant representation of the atomic states and allows for incomplete orthogonal radial orbital functions for the initial and final states. For large lists of configuration state functions, this module also facilitates the computation of transition arrays since the initial and final states need not to be determined in the same run.