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Manuscript Title: HERMES: an optical model search program including tensor potentials for projectile spins 0 to 3/2.
Authors: J. Cook
Program title: HERMES
Catalogue identifier: ABPM_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 31(1984)363
Programming language: Fortran.
Computer: GOULD SEL 32/77.
Operating system: MPX-32 1.5A.
RAM: 275K words
Word size: 32
Peripherals: disc.
Keywords: Optical model central, Tensor, Vector, Neutrons, Deformed potentials, Tensor analysing powers, Charged particles, Spin-orbit, Cross sections, Parameter optimisation, Heavy ions.
Classification: 17.9.

Nature of problem:
The optical model program HERMES calculates cross sections, vector and tensor analysing powers for the elastic scattering of spin 0 to 3/2 projectiles from spin 0 targets, where the optical potential may consist of central, spin-orbit and tensor parts. All possible ranks k of analyzing powers and tensor potentials are included, where 0<k<2s. The program contains a search routine to optimise the optical model parameters to fit experimental data.

Solution method:
A partial wave expansion is made of the distorted waves which leads to uncoupled differential equations when the optical potential contains only central and spin-orbit terms, and coupled equations when tensor potentials are included. These differential equations are solved using a predictor-corrector Numerov integration technique, and the T-matrix is obtained by matching the solutions to Coulomb wavefunctions. Cross sections and analysing powers are calculated from the T-matrix, and a Marguardt algorithm is used to optimise the optical model parameters to fit experimental data.

Restrictions:
(1) Projectile spins 0 to 3/2.
(2) Target spin 0.
(3) No more than 200 partial waves are allowed.
(4) No more than 500 radial integration points.
(5) No more than 800 data points; 100 for the cross sections, and 100 for each of the possible analysing powers.

Running time:
The test calculation of section 1 took 8 minutes.