triqs.operators.util.observables.S2_op
- triqs.operators.util.observables.S2_op(spin_names, n_orb, off_diag=None, map_operator_structure=None, orb_names=None)[source]
Create the square of the total spin operator.
\[\hat S^2 = \hat S_x^2 + \hat S_y^2 + \hat S_z^2.\]- Parameters:
spin_names (list of strings) – Names of the spins, e.g. [‘up’,’down’].
n_orb (int) – Number of orbitals.
off_diag (boolean) – Do we have (orbital) off-diagonal elements? If yes, the operators and blocks are denoted by (‘spin’, ‘orbital’), otherwise by (‘spin_orbital’,0).
map_operator_structure (dict) – Mapping of names of GF blocks names from one convention to another, e.g. {(‘up’, 0): (‘up_0’, 0), (‘down’, 0): (‘down_0’,0)}. If provided, the operators and blocks are denoted by the mapping of
('spin', 'orbital').
- Returns:
S2 – The square of the total spin operator.
- Return type: