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Manuscript Title: The analytical Scheme calculator for angular momentum coupling and recoupling coefficients
Authors: A. Deveikis, A. Kuznecovas
Program title: Scheme2Clebsch
Catalogue identifier: ADWC_v1_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 172(2005)60
Programming language: Scheme (freely available [1]).
Computer: Any Scheme-capable platform.
Operating system: Windows 2000.
RAM: 50 MB (≈ size of DrScheme, version 204).
Keywords: Angular momentum, Clebsch-Gordan coefficient, Wigner n-j symbol, General recoupling coefficient.
PACS: 03.65.-w, 02.70.-c, 03.65.Fd, 02.90.+p.
Classification: 4.1.

Nature of problem:
The accurate and fast calculation of the angular momentum coupling and recoupling coefficients is required in various branches of quantum many-particle physics. The presented code provides a fast and exact calculation of the angular momentum coupling and recoupling coefficients for large values of quantum angular momenta and is based on the GNU Library General Public License PLT software [1].

Solution method:
A direct evaluation of sum formulas. A general angular momentum recoupling coefficient for an arbitrary number of (integer or half-integer) angular momenta is expressed as a sum over products of the Clebsch-Gordan coefficients.

Restrictions:
Limited only by the DrScheme implementation used to run the program. No limitation inherent in the code.

Running time:
The Clebsch-Gordan coefficients, Wigner 6j and 9j symbols, and general recoupling coefficients with small angular momenta are computed almost instantaneously. The running time for large-scale calculations depends strongly on the number and magnitude of arguments' values (i.e. of the angular momenta).

References:
[1] http://www.plt-scheme.org/