Maple procedures for the coupling of angular momenta. V. Recoupling coefficients

Fritzsche S., Inghoff T., Bastug T.

In various fields of physical research, the quantum mechanical description of many-particle processes often requires an explicit transformation of the angular momenta of the subsystems among different coupling schemes. In general, such transformations are given by recoupling coefficients which, consequently, need to be evaluated over and over again in rather different investigations. Here, we present an extension to the RACAH program which supports the application and evaluation of general recoupling coefficients. Compared with a previous version of this program, a considerably faster evaluation has now been achieved by exploiting graphical rules and by making more efficiently use of the symmetries of the Racah expressions. Moreover, a set of interactive help pages for most user-relevant commands now facilitate the handling of the RACAH program and may even support its application in class-room teaching of the theory of angular momentum.