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Manuscript Title: NUCORE, a system for nuclear structure calculations with cluster-core models.
Authors: C.A. Heras, S.M. Abecasis
Program title: NUCORE
Catalogue identifier: AARQ_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 25(1982)237
Programming language: Fortran.
Computer: IBM 4341.
Operating system: DOS/VSE (R2.0 PUT 800).
RAM: 128K words
Word size: 32
Keywords: Nuclear physics, Cluster model, Minimization, Nuclear physics, Cluster model, Minimization, Nuclear energy levels, Quadrupole reduced Electric transition Probabilities, Dipole reduced Magnetic transition Probabilities, Electric quadrupole Moments, Magnetic dipole moments.
Classification: 17.21.

Subprograms used:
Cat Id Title Reference
ACWH_v1_0 MINUIT CPC 10(1975)343

Nature of problem:
Calculation of nuclear energy levels and their electromagnetic properties, modelling the nucleus as a cluster of a few particles and/or holes interacting with a core which in turn is modelled as a quadrupole vibrator (cluster-phonon model). The members of the cluster interact via quadrupole-quadrupole and pairing forces.

Solution method:
The Hamiltonian matrix is diagonalized taking single-particle energies and interaction strength constants as adjustable parameters determined by fitting calculated to experimental energy levels through chi-square minimization. The resulting eigenvalues and eigenvectors are used to calculate electromagnetic properties of the levels.

Restrictions:
1) The subroutine PHONON and CO2HIP are restricted to a maximum number of two phonons. The dimensions of the arrays depend rather strongly on this. It must be pointed out that for a given number of phonons the dimensions are also modified according to the different number of single-particle orbitals needed for different nuclei.
2) The first run of program no. 2 depends essentially on the use of the system MINUIT. Modification of the code might be needed with alternative minimizing routines.
3) The actual code is designed for diagonalizing routines using only non-zero matrix elements.
4) The present version of the code applies to cases in which only one level parity is implied. However, slight modifications allow the program to be used when both parties are involved.

Unusual features:
To maximize the utility of the program, the following features are provided.
1)The MAIN simple and most flexible with the "physics" included in routines. Thus, it can be adapted to manage different nuclear models within the same computational framework.
2)The routines are designed in such a way that they have non-dimensioned variables or variable-dimensioned ones, thus greatly reducing storage requirements.
3)The program permits the use of alternative routines to calculate radial integrals, to diagonalize matrices, and to minimize the desired functions.
4)The subroutine FCN is so implemented that it may be used without any minimization. Therefore, the same MAIN program is used to perform different tasks.

Running time:
The execution time is strongly problem dependent. The test runs, which involve the building and diagonalization of a 63*63 matrix with a total of 617 non-zero elements, and the computation of the electromagnetic properties for three calculated energy levels, require a total of 24 min (including 17 min of compilation time).