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Manuscript Title: A general program to calculate atomic continuum processes incorporating model potentials and the Breit-Pauli Hamiltonian within the R-matrix method.
Authors: N.S. Scott, K.T. Taylor
Program title: RMATRX STG1R
Catalogue identifier: AANR_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 25(1982)347
Programming language: Fortran.
Computer: CRAY-1.
Operating system: COS 1.09.
RAM: 169K words
Word size: 64
Peripherals: magnetic tape, disc.
Keywords: Atomic physics, Electron-atom, Scattering, Electron-ion, Photoionization, Polarizability, R-matrix, Continuum, Bound, De vogelaere's method, Radial integrals, Rk integrals, Model-potential, Mass-correction, Darwin term, Spin-orbit, Pair-coupling, Breit-pauli hamiltonian, Relativistic effects, Fine structure levels, Photon.
Classification: 2.4, 2.5.

Subprograms used:
Cat Id Title Reference
AANS_v1_0 RMATRX STG2R CPC 25(1982)347
AANT_v1_0 RMATRX RECUP CPC 25(1982)347
AANU_v1_0 RMATRX RECUD CPC 25(1982)347
AANV_v1_0 RMATRX STG3R CPC 25(1982)347

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
ADCP_v1_0 RMATRX1 CPC 92(1995)290

Nature of problem:
This program calculates all one-electron, two-electron and multipole radial integrals involving bound and continuum orbitals. These radial integrals enable the calculation of electron scattering and photoionization cross-sections for a general atomic system. Cross- sections between fine structure levels may be obtained by introducing relativistic effects through the Breit-Pauli Hamiltonian and pair coupling. The closed shell core of the target atom may be approximated by a model potential. The bound orbitals are specified analytically. The continuum orbitals are calculated by the program. The integrals are stored on a magnetic tape or disc file for use by RMATRX STG3R.

Solution method:
The continuum orbitals are determined by integrating numerically a differential equation with a given potential using de Vogelaere's method and subject to R-matrix boundary conditions. The radial integrals are evaluated numerically using Simpson's rule.

Restrictions:
The Schmidt orthogonalisation procedure may not be used if relativistic operators are included in the Hamiltonian. Consult subroutine SETDIM of RMATRIX STGIR for details of current dimensions.

Running time:
The running time depends approximately on the square of the number of bound orbitals, on the square of the number of continuum orbitals for each angular momentum and on the number of comtinnum angular momenta. The test run took 15 s on the CRAY-1.