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Manuscript Title: Generalized fractional parentage coefficients for shell-model calculations.
Authors: L.D. Skouras, S. Kossionides
Program title: GFPCM
Catalogue identifier: AADY_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 39(1986)197
Programming language: Fortran.
Computer: PRIME-750.
Operating system: PRIMOS VERSION 18.3 UPWARDS.
RAM: 133K words
Peripherals: disc.
Keywords: Nuclear physics, Antisymmetry, Angular momentum, Isospin, Fractional parentage Coefficients.
Classification: 17.18.

Subprograms used:
Cat Id Title Reference
AAFC_v1_0 RWSYST CPC 39(1986)213

Nature of problem:
In a space defined by several single-particle orbitals anti-symmetric states for any n-fermion system can be expanded in terms of states which are antisymmetric only with respect to the first m and the last (n-m) particles. These (m, n-m) expansion coefficients, the Generalized Fractional Parentage Coefficients (gfpc), can then be used to determine easily the matrix elements of any m-body operator. The states are classified according to C which denotes the distribution of the n particles among the orbitals, their total angular momentum J and isospin T and an index mu that distinguishes the orthogonal states that have the same C, J, T values. Program GFPCM calculates the (m,n-m)gfpc for 2 < m < n. It shares its long write-up with program GFPC1 which constructs the coefficients for m = 1, the (1,n-1) gfpc.

Solution method:
The program calculates the (m, n-m) gfpc with recursive formulae involving the (1, n-1) and (m-1, n-m) gfpc. Thus GFPC1 and GFPCM must first create these files.

The complexity is restricted only by the available Disk space for storage of the gfpc.

Unusual features:
The program is written in standard FORTRAN-77 and can easily be transported. All machine dependent characteristics (e.g. word length, file units, array dimensions) are set with PARAMETER statements and can easily be adapted. The program will produce the complete set of gfpc in one or several consecutive runs. Upon entry it will determine the point to which the gfpc-file has been completed and continue to the point determined by the input data. For all error conditions, error messages will be printed.

Running time:
It depends on the complexity of the problem and averages to about 10 coefficients per second on the PRIME-750.