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

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.