triqs.operators.util.U_matrix.reduce_4index_to_2index

triqs.operators.util.U_matrix.reduce_4index_to_2index(U_4index)[source]

Reduces the four-index matrix to two-index matrices for parallel and anti-parallel spins.

Parameters:

U_4index (float numpy array) – The four-index interaction matrix.

Returns:

  • U (float numpy array) – The two-index interaction matrix for parallel spins.

  • Uprime (float numpy array) – The two-index interaction matrix for anti-parallel spins.