Programs in Physics & Physical Chemistry
|[Licence| Download | New Version Template] adfj_v1_0.gz(9 Kbytes)|
|Manuscript Title: Calculation of general recoupling coefficients using graphical methods.|
|Authors: V. Fack, S.N. Pitre, J. Van der Jeugt|
|Program title: NEWGRAPH|
|Catalogue identifier: ADFJ_v1_0|
Distribution format: gz
|Journal reference: Comput. Phys. Commun. 101(1997)155|
|Programming language: C.|
|Computer: 486-based PCs.|
|Operating system: MS-DOS, Linux, Unix.|
|Keywords: General purpose, Rotation group, Atomic structure, Nuclear structure, Scattering, General recoupling Coefficient, Angular momentum, Racah coefficient, Sn-j coefficient, Coupling tree, Binary trees, Yutsis graphs.|
|ADBA_v1_0||NJSUMMATION, NJSUMPAR||CPC 86(1995)105|
Nature of problem:
A general recoupling coefficient for an arbitrary number of (integer or half-integer) angular momenta is expressed as a multiple sum over products of 6-j coefficients, including phase factors and square root factors. This summation formula can then be evaluated for given values of the angular momenta (for this purpose we use the program NJSUMMATION ).
A summation formula for a general recoupling coefficient is obtained by representing the coefficient by a Yutsis graph, and by performing a number of reduction rules valid for such graphs. Each reduction rule contributes to the final summation formula either just by a numerical factor, or else by an additional summation variable. The purpose is to find an optimal summation formula, i.e. with a minimum number of summation variables. With this in mind special attention is paid to implementing the graphical rules whereby N-cycles are reduced in the most optimal way.
The program has been tested using the Linux  operating system. The compilers TURBO C++ , GNU CC  and SPARCompiler C were used.
less than 0.1 s on a 486-based PC running Linux.
|||Linux version 2.0.0 (Unix clone for 386/486-based PCs); publicly available via the Internet, see e.g. http://www.yahoo.com/Computers/Operating_Systems/Unix/Linux/.|
|||Turbo C++ version 1.01, User Guide (Borland, 1990).|
|||GNU CC version 2.5 (Free Software Foundation, Cambridge, MA, USA); publicly available via the Internet, see e.g. http://www.gnu.ai.mit.edu/home.html.|
|||V. Fack, S.N. Pitre, J. Van der Jeugt, Comput. Phys. Commun. 86(1995)105.|
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