CGC : Clebsch-Gordan Coupling Coefficients
About CGC
CGC is a small C library and test program for calculating high order Clebsch-Gordan coupling coefficients. Here, high order means principal quantum numbers of up to about 260 in ordinary double precision and 400 or more in long double precision. When using the GMP arbitrary precision math library, there is essentially no limit on the maximum quantum numbers. The code was written by late Dave Ritchie.
CGC was developed on a 64-bit Linux system, but it should be possible to compile it on Mac OS X or Windows. The only external pre-requisite is the GMP multiple precision math library.
Download CGC 1.0.0
CGC is released under the Gnu LGPL licence. This means you can include it in your own code.
CGC 1.0.0 (to be updated, currently not working)
CGC Documentation and Examples
A brief README file is included in the software installation.
References
The following publication describes the CGC algorithm:
- Whole Number Recursion Formulae for High Order Clebsch-Gordan Coupling Coefficients. D.W. Ritchie, 2018. Inria Report
See also another work by G. Xu, using a Python library:
-
Improved recursive computation of Clebsch-Gordan coefficients. Guanglang Xu, Journal of Quantitative Spectroscopy and Radiative Transfer, 254, 107210 (2020).
Acknowledgements
Dave Ritchie passed away prematurely on Sept 15, 2019. His open-mindedness and scientific contributions continue to inspire us.
Contact
Sjoerd de Vries
SISR LORIA
Campus Scientifique
BP239
54500 Vandoeuvre-lès-Nancy
sjoerd.devries AT loria.fr
