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Manuscript Title: RMATRX1: Belfast atomic R-matrix codes.
Authors: K.A. Berrington, W.B. Eissner, P.H. Norrington
Program title: RMATRX1
Catalogue identifier: ADCP_v1_0 Distribution format: gz
Journal reference: Comput. Phys. Commun. 92(1995)290
Programming language: Fortran.
Computer: Cray Y-MP EL.
Operating system: UNIX, VMS, extended DOS.
RAM: 2M words
Word size: 64
Peripherals: disc.
Keywords: Atomic physics, Electron atom, Scattering, Photon, Electron ion scattering, Photoionization, Polarizability, R-matrix.
Classification: 2.4, 2.5.
Other versions:
Cat Id	Title	Reference
AAHA_v1_0	RMATRX STG1	CPC 8(1974)149
AAHF_v1_0	A NEW VERSION OF RMATRX STG1	CPC 14(1978)367
AANR_v1_0	RMATRX STG1R	CPC 25(1982)347
Nature of problem: This program uses the R-matrix method to calculate electron-atom and electron-ion collision processes, with options to calculate radiative data, photoionization etc. Calculations can be either in LS-coupling or in an intermediate-coupling scheme. The program is based on two earlier CPC programs [1,7], with extensions by the Opacity Project [2,8] and the Iron Project team [6].
Solution method: The R-matrix method is used [3,4,5]. The code is written for an LS- coupling scheme, with options to include Breit-Pauli terms in the Hamiltonian and recouple the matrices to an intermediate-coupling scheme.
Reasons for new version: incorporate new sections for calculating radiative data; merge the LS-coupling and Breit-Pauli versions; implement new algorithms, better numerical procedures, etc.; improve optimisation (e.g. vectorisation, reducing I/O); upgrade to FORTRAN 77; allow preprocessing of arrays.
Restrictions: The main purpose of the present publication is to publish the internal region modules. The external region module (STG4) is rather inefficient and should be replaced in production runs.
Unusual features: Dimensions can be reset by preprocessing.
Running time: The test runs take about 2 minutes on a Cray Y-MP EL. However this is a small atypical calculation. The running time in a realistic calculation tends to be dominated by three processes: (a) calculating angular integrals in STG2, particularly for open d-shell targets; (b) diagonalizing large Hamiltonian matrices in STGH, an n**3 process, where n is the size of the Hamiltonian and is proportional to the number of channels and basis terms. (c) solving the coupled equations in the external region, depends on the number of scattering energies required as well as the number of channels.
References:
[1]	Berrington K.A., Burke P.G., Le Dourneuf M. Robb W.D., Taylor K.T. and Vo Ky Lan, Comput. Phys. Commun. 14(1978)367-412.
[2]	Berrington K.A., Burke P.G., Butler K., Seaton M.J., Storey P.J., Taylor K.T. and Yu Yan, J. Phys. B: At. Mol. Phys. 20(1987)6379-97.
[3]	Burke P.G. and Berrington K.A., Atomic and Molecular Processes, an R-matrix Approach (Institute of Physics Publ. Bristol) ISBN 0-7503-0199-6 (1993).
[4]	Burke P.G. and Robb W.D., Adv. At. Mol. Phys. 11(1975)143-214.
[5]	Burke P.G., Hibbert A. and Robb W.D., J. Phys. B: At. Mol. Phys. 4(1971)153-61.
[6]	Hummer D.G., Berrington K.A., Eissner W., Pradhan A.K., Saraph H.E. and Tully J.A., Astron. Astrophys. 279(1993)298-309.
[7]	Scott N.S. and Taylor K.T., Comput. Phys. Commun. 25(1982)347-87.
[8]	Seaton M.J., J. Phys. B: At. Mol. Phys. 20(1987)6363-78.