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Manuscript Title: Coulomb plus strong interaction bound states - momentum space numerical solutions.
Authors: D.P. Heddle, Y.R. Kwon, F. Tabakin
Program title: BOPIT
Catalogue identifier: AADM_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 38(1985)71
Programming language: Fortran.
Computer: VAX 11-780, DEC-20.
Operating system: VMS.
RAM: 307K words
Word size: 32
Keywords: Nuclear physics, Shell model, Coulomb, Bound state, Hadronic atoms, Level shifts, Level widths, Momentum space, Schrodinger equation, Dirac equation, Klein-gordon equation.
Classification: 17.19.

Revision history:
Type Tit le Reference
adaptation 0001 AUTOMATIC GRIDPOINT METHOD See below

Nature of problem:

Solution method:
The levels and widths of hadronic atoms are calculated in momentum space using an inverse algorithm for the eigenvalue problem. The Coulomb singularity is handled by the Lande subtraction method. Relativistic, nonlocal, complex hadron nucleus interactions are incorporated as well as vaccum polarization and finite size effects. Coordinate space wavefunctions are obtained by employing a Fourier Bessel transformation.

Restrictions:
A maximum of 100 grid points can be used. This can be trivially modified by changing the dimensions of various arrays.

Running time:
For the point Coulomb case with 20 grid points approximately 1 s CPU time, for 40 grid points approximately 5 s CPU time.

ADAPTATION SUMMARY
Manuscript Title: Adaptation of Coulomb plus strong interaction bound states - momentum space solutions: automatic gridpoint method.
Authors: R.J. Luce, F. Tabakin
Program title: 0001 AUTOMATIC GRIDPOINT METHOD
Catalogue identifier: AADM_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 46(1987)193
Programming language: Fortran.
Computer: VAX 8650.
Word size: 32
Classification: 17.19.

Nature of problem:
To solve the Schroedinger, Klein-Gordon, and Dirac equations for the bound state eigenvalues and wavefunctions for hadronic atoms, where the Coulomb and strong interactions are described in momentum space.

Solution method:
A matrix method is used which entails a suitable set of discrete momentum space gridpoints. Starting from a guess for the real and imaginary eigenvalues, the energy shifts and widths are obtained rapidly for each quantum state using an inverse iteration technique. The reason for the Adaptation is to automate the choice of momentum space grid- points based on the atomic and nuclear sizes so that the code can be more conveniently used for analysis of hadronic atoms, and to include several other corrections and improvements.

Restrictions:
The total number of gridpoints is restricted to 100 points and the potential must be stipulated as bounded quantities in momentum space, i.e. they must be nonsingular interactions.

Running time:
On the VAX 8650 for 50 gridpoints the code takes 2.75 seconds CPU time and 15.48 seconds CPU for the 100 point sample case given later.