Evaluating Wigner D-matrices

This repository contains codes in C++, Fortran and Python to evaluate the Wigner D-matrix.

The Fortran and Python version use the algorithm described by Choi et al.¹, which resursively computes the individual matrix elements.

The C++ version uses the diagonalization approach by Feng et al.². The relevant matrices are diagonalized using LAPACK.

Footnotes

1. Choi, C. H., Ivanic, J., Gordon, M. S., & Ruedenberg, K. (1999). Rapid and stable determination of rotation matrices between spherical harmonics by direct recursion. The Journal of Chemical Physics, 111(19), 8825-8831 ↩

2. Feng, X. M., Wang, P., Yang, W., & Jin, G. R. (2015). High-precision evaluation of Wigner's d matrix by exact diagonalization. Physical Review E, 92(4), 043307 ↩