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Manuscript Title: MCBP: a program to calculate angular coefficients of the Breit interaction between electrons in the low energy limit.
Authors: N. Beatham, I.P. Grant, B.J. McKenzie, N.C. Pyper
Program title: MCBP-BREIT ANGULAR COEFFICIENTS
Catalogue identifier: AAAL_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 18(1979)245
Programming language: Fortran.
Computer: IBM 360/195.
Operating system: OS/360, HASP.
RAM: 176K words
Word size: 8
Peripherals: disc.
Keywords: Atomic physics, Racah, Configuration Interaction, Fractional parentage, Recoupling coefficients, Slater integrals, Complex atoms, Relativistic, Dirac equation, Retarded interaction, Breit, Jj-coupling, Theoretical methods.
Classification: 2.9.

Subprograms used:
Cat Id Title Reference
AAGD_v2_0 NJSYM CPC 8(1974)151
ACRI_v1_0 CFPJJ - CFP IN JJ-COUPLING CPC 4(1972)377
ACWE_v1_0 MCP75 CPC 11(1976)397

Nature of problem:
The retarded interaction between a pair of electrons makes a non- negligible contribution to atomic energy levels especially in processes such as X-ray emission and absorption and Auger spectroscopy, involving inner shell holes. This program handles the algebraic part of this calculation using the formulation of Grant and Pyper and lists the coefficients of radial integrals in a form suitable for use with the wavefunctions produced by multiconfiguration Dirac-Fock programs, such as that of Grant, Mayers and Pyper. The input to this program is identical with that used in MCP75.

Restrictions:
The program assumes that all open shell configuration state functions are formed from the same orthonormal set of basis orbitals. The number of electrons in a shell having j>=9/2 is restricted to be not greater than 2 by the available c.f.p. tables. The present version allows up to 10 open or closed shell orbitals and 30 configurational states with up to 6000 coefficients. These numbers can be changed by the user. It is advisable to ensure that the library subprograms AAHD and ACRI have been converted to use double precision floating point arithmetic when implementing the package on IBM machines.