triqs.operators.util.observables.L2_op
- triqs.operators.util.observables.L2_op(spin_names, n_orb, off_diag=None, map_operator_structure=None, basis='spherical', T=None, orb_names=None)[source]
Create the square of the orbital momentum operator.
\[\hat L^2 = \hat L_x^2 + \hat L_y^2 + \hat L_z^2.\]- 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').basis (string, optional) –
The basis in which the interaction matrix should be computed. Takes the values
’spherical’: spherical harmonics,
’cubic’: cubic harmonics (valid only for the integer orbital momenta, i.e. for odd values of n_orb),
’other’: other basis type as given by the transformation matrix T.
T (real/complex numpy array, optional) – Transformation matrix for basis change. Must be provided if basis=’other’.
- Returns:
L2 – The square of the orbital momentum operator.
- Return type: