Parameter: isspn

Definition

Key control flag, determine the symmetry of spin orientation freedom of degree.

Type

Integer

Default value

1

Component

ALL

Behavior

There are two possible values for the isspn parameter so far:

• isspn = 1, enforce spin up = spin down.

• isspn = 2, let spin up and spin down states evolve independently.

The quantum impurity solvers will symmetrize the relevant physical quantities according to the isspn parameter.

Comment

Usually, the isspn and issun are used at the same time to setup the magnetic order of the system. For example, if you want to simulate a model with anti-ferromagnetic order, then isspn should be 2, and issun can be 1 or 2 (a solver.eimp.in file must be available for the latter case).

See issun parameter for more details.