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Manuscript Title: HFS92: a program for relativistic atomic hyperfine structure calculations.
Authors: P. Jonsson, F.A. Parpia, C.F. Fischer
Program title: HFS92
Catalogue identifier: ADDN_v1_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 96(1996)301
Programming language: Fortran.
Computer: IBM RS/6000-530.
Operating system: IBM AIX 3.2.5+.
Word size: 32
Keywords: Atomic hyperfine, Structure, Atomic physics, Hyperfine interaction, A factor, B factor, Hyperfine quenching in, Atoms, Multiconfiguration, Dirac-fock, Configuration Interaction.
Classification: 2.1.

Subprograms used:
Cat Id Title Reference
ADCU_v1_0 GRASP92 CPC 94(1996)249

Nature of problem:
Prediction of atomic hyperfine structure using a 'fully relativistic' approach.

Solution method:
The state of the electron cloud is assumed to be given by a wavefunction of the form |GammaJ P J MJ> = Sigmar cr|gammar P J MJ>, where J and MJ are, respectively, the total angular and momentum and 'magnetic' quantum numbers, P = +- (1) is the parity quantum number. The configuration state functions |gammar P J MJ> are constructed from linear combinations of Slater determinants of four-component spin-orbitals. The state of the nucleus is assumed to be independent of that of the electrons, and is denoted |GammaI I MI>. The atomic state is assumed to be a tensor product of the nuclear and electronic states. Upon expressing the interaction between the nucleus and the electrons as a multipole expansion, the methods of Racah algebra may be used to separate the matrix elements into linear combinations of products of purely nuclear and purely electronic reduced matrix elements [1]. Empirical values of the nuclear electromagnetic moments are combined with computed electronic electromagnetic moments to estimate the hyperfine interaction elements and constants. Evaluation of the reduced matrix element between configuration state functions is done using a program originally written by Pyper, Grant and Beatham [2], where angular recoupling programs are set up to reduce the matrix elements to terms that involve single particles only. In the present implementation of the latter program, the angular recoupling coefficients required are computed using the NJGRAF package of Bar Shalom and Klapisch [3].

The complexity of the cases that can be handled is entirely determined by the GRASP92 package [4] used for the generation of the electronic wavefunctions.

[1] I. Lindgren and A. Rosen, Case Stud. At. Phys. 4(1974)93.
[2] N.C. Pyper, I.P. Grant and N. Beatham, Comput. Phys. Commun. 15(1978)387.
[3] A. Bar Shalom and M. Klapisch, Comput. Phys. Commun. 50(1988)375.
[4] F.A. Parpia, C. Froese Fischer and I.P. Grant, Comput. Phys. Commun. 94(1996)249.