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Manuscript Title: Matrix elements of the reaction matrix in finite nuclei.
Authors: R.J.W. Hodgson
Program title: REACTION MATRIX
Catalogue identifier: ABIF_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 11(1976)113
Programming language: Fortran.
Computer: IBM 360/65.
Operating system: HASP OS/360 LEVEL 21.8.
RAM: 52K words
Word size: 32
Peripherals: magnetic tape.
Keywords: Nuclear physics, Finite nuclei, Reaction matrix, Compound nucleus.
Classification: 17.10.

Subprograms used:
Cat Id Title Reference

Nature of problem:
Matrix elements of the raction matrix in finite nuclei are computed in the relative center-of-mass (RCM) harmonic-oscillator representation. A harmonic oscillator Pauli operator is employed together with purely kinetic particle states. The approach used follows that of Sauer. The Reid soft-core potential is employed in the code discussed.

Solution method:
A reference reaction matrix is first computed by matrix inversion, and harmonic-oscillator matrix elements of this evaluated by a double inte- gration. The reaction matrix elements can then be determined by solving a set of linear algebraic equations.

Matrix inversion is used to solve for the reference reaction matrix, as well as in the evaluation of the operators involved in the determination of the reaction matrix. The maximum dimension allowed is 16. However very good results are obtained using a dimension of 6.

Unusual features:
During the first run of ABIF(REACTION MATRIX), data is output for use with ABIE(REFERENCE REACTION MATRIX), which in turn outputs required data of subsequent runs of ABIF.

Running time:
The run of REACTION MATRIX to obtain a punched data deck takes approximately 5 s for each 10 matrix elements. REFERENCE REACTION MATRIX requires roughly 10 s for each 4 T-matrix elements. This figure was obtained from the test run. If a large number of elements are computed, this figure improves, as more use is made of stored intermediate results. REACTION MATRIX needs about 10 s for each 5 matrix elements. Both these times are exclusive of compile times.