amc 0.9.1

Automatic angular-momentum reduction

In quantum many-body theory, one often encounters problems with rotational symmetry. While methods are most conveniently derived in schemes that do not exploit the symmetry, a symmetry-adapted formulation can lead to orders of magnitude savings in computation time. However, actually reducing the formulas of a many-body method to symmetry-adapted form is tedious and error-prone.

The AMC package aims to help practitioners by automating the reduction process. The unreduced (m-scheme) equations can be entered via an easy-to-use language. The package then uses Yutsis graph techniques to reduce the resulting network of angular-momentum variables to irreducible Wigner 6j and 9j symbols, and outputs the reduced equations as a LaTeX file. Moreover, the package is based on abstract representations of the unreduced and reduced equations in the form of syntax trees, which enable other uses such as automatic generation of code that computes the reduced equations.