triqs.operators.util.observables.S_op

triqs.operators.util.observables.S_op(component, spin_names, n_orb, off_diag=None, map_operator_structure=None, orb_names=None)

Create a component of the spin vector operator.

\[\hat{S}_{x,y,z} = \frac{1}{2}\sum_{i\sigma\sigma'} \hat{c}^\dagger_{i\sigma} \mathbf{\tau}^{x,y,z}_{\sigma\sigma'} \hat{c}_{i\sigma'}, \quad\hat{S}_\pm = \hat{S}_x \pm i \hat{S}_y.\]

Parameters:

componentstr

Component to be created, one of 'x', 'y', 'z', '+' or '-'.

spin_nameslist of str

Names of the spins, e.g. ['up', 'down'].

n_orbint

Number of orbitals.

off_diagbool, optional

If True, operators and blocks are labelled by ('spin', 'orbital'); otherwise by ('spin_orbital', 0).

map_operator_structuredict, optional

Mapping of GF-block names from one convention to another, e.g. {('up', 0): ('up_0', 0), ('down', 0): ('down_0', 0)}. If provided, the operators and blocks use the image of ('spin', 'orbital') under this map.

Returns:

Operator

The requested component of the spin vector operator.