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Manuscript Title: A general program to calculate angular momentum coefficients in relativistic atomic structure. See erratum Comp. Phys. Commun. 6(1973)98.
Authors: I.P. Grant
Program title: MCP
Catalogue identifier: ACRJ_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 5(1973)263
Programming language: Fortran.
Computer: ICL 1906A.
Operating system: GEORGE 3, MARK 6.3.
RAM: 32K words
Word size: 24
Keywords: Atomic physics, Racah, Configuration Interaction, Coefficients of Fractional parentage, Recoupling coefficients, Slater integrals, Complex atoms, Dirac equation, Bound states, Jj-coupling, Relativistic, Theoretical methods.
Classification: 2.9.

Subprograms used:
Cat Id Title Reference
AAGD_v1_0 NJSYM CPC 1(1970)241
AAGD_v1_0 0002 ADAPT TO INTEGER ARITHMETIC CPC 5(1973)161
ACRI_v1_0 CFPJJ-CFP IN JJ-COUPLING CPC 4(1972)377

Other versions:
Cat Id Title Reference
ACWE_v1_0 MCP75 CPC 11(1976)397

Revision history:
Type Tit le Reference
correction 000A CORRECTION 10/06/76 See below
correction 000B CORRECTION 2/02/77 See below

Nature of problem:
A number of relativistic atomic structure programs have recently become available, for example the self-consistent field programs of Liberman, Cromer and Waber (CPC 2 (1971) 107, 2 (1971) 471). This makes it possible to consider carrying out configuration interaction calculations using Dirac wave functions. As in the non-relativistic theory, the major difficulty is to determine the two-electron matrix elements of the interelectronic interaction. This program calculates the coefficients of Slater integrals in terms of which the matrix elements can be expressed.

Solution method:
The coefficients of Slater integrals can be derived by combining the standard expressions of the relativistic formulation with the schemes of Fano or Armstrong. As in the equivalent non-relativistic program of Hibbert, the coefficients can be expressed as a sum of terms incorporat- ing products of fractional parentage coefficients, recoupling coefficients and reduced matrix elements. Configurations are defined by the number of electrons in each occupied shell, the (nja) quantum numbers and angular momentum couplings.

Restrictions:
Any number of electrons (<= 2j+1) are allowed in shells with j= 1/2, 3/2, 5/2, 7/2 but no more than two electrons in any shell of higher angular momentum. It would be possible to relax this restriction with a more comprehensive package of coefficients of fractional parentage. The version submitted allows up to 10 orbitals and 30 configurations. The orbitals may be distributed in any manner between the filled shells of the "core" and the open shells in the "peel". Limits in COMMON and DIMENSION statements appear in the long write-up.

Running time:
The time required for the test run is 1.5 min on an ICL 1906A, of which ~~17 s is taken in execution.

CORRECTION SUMMARY
Manuscript Title: Appendix to a program to calculate angular momentum coefficients in relativistic atomic structure - revised version. (C.P.C. 5(1973)263).
Authors: I.P. Grant
Program title: 000A CORRECTION 10/06/76
Catalogue identifier: ACRJ_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 11(1976)397
Classification: 2.9.

CORRECTION SUMMARY
Manuscript Title: A general program to calculate angular momentum coefficients in relativistic atomic structure. (C.P.C. 5(1973)263).
Authors: I.P. Grant
Program title: 000B CORRECTION 2/02/77
Catalogue identifier: ACRJ_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 13(1977)429
Classification: 2.9.