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Manuscript Title: Weizmann shell model computational code.
Authors: R. Gross, Y. Accad
Program title: WSMCC
Catalogue identifier: ABGN_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 8(1974)101
Programming language: Fortran.
Computer: IBM 370/165.
Operating system: OS360.
RAM: 70K words
Word size: 32
Peripherals: magnetic tape.
Keywords: Nuclear physics, Cfp, Wave functions, Shell model, J-j coupling, Seniority, Spin, Isospin, Configuration, Coupling, Recoupling of Angular momenta.
Classification: 17.19.

Subprograms used:
Cat Id Title Reference
ABKB_v1_0 JJTCFP CPC 1(1970)225

Nature of problem:
WSMCC is a computer program which carries out nuclear shell-model /spectroscopy) calculations. Given the total number of particles, total angular momentum and total isospin, the program calculates the energy levels and eigenstates as functions of the two-body matrix elements and the single particle energies.

Solution method:
Calculations are carried out by reducing the problem to the two-body matrix elements, using the well-known shell-model formalism . The current version of the program can handle large configurations as well as small ones, and it is able to calculate any matrix element of a two- body scalar operator in one, two or three shells. For more than three shells, the program can be extended by recoupling the angular momenta of the n particles in the wave function so that all unchanged (n-2) particles will be coupled together (this extension is available, but is not included in the current version).

Calculations are done in double-precision mode (each number occupies two 32-bit words in memory). The above mentioned high speed storage size includes an array of about 6500 cfp's and a hamiltonian matrix of 45 by 45. In case of a larger matrix, the elements are written out as they are computed for later diagonalization.

Unusual features:
The input coefficients of fractional parentage (cfp) cards can be taken with their original format from Comp. Phys. Commun. 1(1970)225. Most of the subroutines can be used alone for different calculations using the shell-model formalism.

Running time:
Running time depends roughly on the square of the order of the hamilton- ian matrix, the vaules of total and intermediate spins and isospins; number of particles and configurations; the spin of the configuration; whether the classification of the states is read in or calculated bythe program; and many others. To give an order of magnitude for the running time we mention that for the caluclation of the 21 states of 36Ar with zero angular momentum and isospin, the present version needs about 13 s on an IBM 370/165; the same calculation for the 325 states (with J=0 and T=0) of 24Mg needs about 20 m and for the 21 states of 20Ne only 2 s. So it is qute meaningless to speak about a "typical" running time.