177 research outputs found
Pure spin-angular momentum coefficients for non-scalar one-particle operators in jj-coupling
A revised program for generating the spin-angular coefficients in
relativistic atomic structure calculations is presented. When compared with our
previous version [G.Gaigalas, S.Fritzsche and I.P.Grant, CPC 139 (2001) 263],
the new version of the Anco program now provides these coefficients for both,
scalar as well as non-scalar one-particle operators as they arise frequently in
the study of transition probabilities, photoionization and electron capture
processes, the alignment transfer through excited atomic states, collision
strengths, and in many other investigations.
The program is based on a recently developed formalism [G.Gaigalas,
Z.Rudzikas, and C.F.Fischer, J. Phys. B 30 (1997) 3747], which combines
techniques from second quantization in coupled tensorial form, the theory of
quasispin, and the use of reduced coefficients of fractional parentage, in
order to derive the spin-angular coefficients for complex atomic shell
structures more efficiently. By making this approach now available also for
non-scalar interactions, therefore, studies on a whole field of new properties
and processes are likely to become possible even for atoms and ions with a
complex structure
Maple procedures for the coupling of angular momenta. VI. LS-jj transformations
Transformation matrices between different coupling schemes are required, if a
reliable classification of the level structure is to be obtained for open-shell
atoms and ions. While, for instance, relativistic computations are
traditionally carried out in jj-coupling, a LSJ coupling notation often occurs
much more appropriate for classifying the valence-shell structure of atoms.
Apart from the (known) transformation of single open shells, however, further
demand on proper transformation coefficients has recently arose from the study
of open d- and f-shell elements, the analysis of multiple--excited levels, or
the investigation on inner-shell phenomena. Therefore, in order to facilitate a
simple access to LS jj transformation matrices, here we present an
extension to the Racah program for the set-up and the transformation of
symmetry-adapted functions. A flexible notation is introduced for defining and
for manipulating open-shell configurations at different level of complexity
which can be extended also to other coupling schemes and, hence, may help
determine an optimum classification of atomic levels and processes in the
future
Optimal classification of HCI spectra
Energy levels of highly charged ions as a rule cannot be classified using LS
coupling due to rapid increase of relativistic effects. It is suggested, for
optimal classification of energy spectra, to calculate them in LS coupling and
to transform the weights of the wave functions, obtained after diagonalization
of the energy matrix, to the other coupling schemes. F-like ions are considered
as an example
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