SpinHalfSite

Inheritance Diagram

Inheritance diagram of tenpy.networks.site.SpinHalfSite

Methods

SpinHalfSite.__init__([conserve])

Initialize self.

SpinHalfSite.add_op(name, op[, need_JW])

Add one on-site operators.

SpinHalfSite.change_charge([new_leg_charge, …])

Change the charges of the site (in place).

SpinHalfSite.from_hdf5(hdf5_loader, h5gr, …)

Load instance from a HDF5 file.

SpinHalfSite.get_op(name)

Return operator of given name.

SpinHalfSite.multiply_op_names(names)

Multiply operator names together.

SpinHalfSite.op_needs_JW(name)

Whether an (composite) onsite operator is fermionic and needs a Jordan-Wigner string.

SpinHalfSite.remove_op(name)

Remove an added operator.

SpinHalfSite.rename_op(old_name, new_name)

Rename an added operator.

SpinHalfSite.save_hdf5(hdf5_saver, h5gr, subpath)

Export self into a HDF5 file.

SpinHalfSite.state_index(label)

Return index of a basis state from its label.

SpinHalfSite.state_indices(labels)

Same as state_index(), but for multiple labels.

SpinHalfSite.test_sanity()

Sanity check, raises ValueErrors, if something is wrong.

SpinHalfSite.valid_opname(name)

Check whether ‘name’ labels a valid onsite-operator.

Class Attributes and Properties

SpinHalfSite.dim

Dimension of the local Hilbert space.

SpinHalfSite.onsite_ops

Dictionary of on-site operators for iteration.

class tenpy.networks.site.SpinHalfSite(conserve='Sz')[source]

Bases: tenpy.networks.site.Site

Spin-1/2 site.

Local states are up (0) and down (1). Local operators are the usual spin-1/2 operators, e.g. Sz = [[0.5, 0.], [0., -0.5]], Sx = 0.5*sigma_x for the Pauli matrix sigma_x.

operator

description

Id, JW

Identity \(\mathbb{1}\)

Sx, Sy, Sz

Spin components \(S^{x,y,z}\), equal to half the Pauli matrices.

Sigmax, Sigmay, Sigmaz

Pauli matrices \(\sigma^{x,y,z}\)

Sp, Sm

Spin flips \(S^{\pm} = S^{x} \pm i S^{y}\)

conserve

qmod

excluded onsite operators

'Sz'

[1]

Sx, Sy, Sigmax, Sigmay

'parity'

[2]

None

[]

Parameters

conserve (str) – Defines what is conserved, see table above.

conserve

Defines what is conserved, see table above.

Type

str

add_op(name, op, need_JW=False)[source]

Add one on-site operators.

Parameters
  • name (str) – A valid python variable name, used to label the operator. The name under which op is added as attribute to self.

  • op (np.ndarray | Array) – A matrix acting on the local hilbert space representing the local operator. Dense numpy arrays are automatically converted to Array. LegCharges have to be [leg, leg.conj()]. We set labels 'p', 'p*'.

  • need_JW (bool) – Whether the operator needs a Jordan-Wigner string. If True, the function adds name to need_JW_string.

change_charge(new_leg_charge=None, permute=None)[source]

Change the charges of the site (in place).

Parameters
  • new_leg_charge (LegCharge | None) – The new charges to be used. If None, use trivial charges.

  • permute (ndarray | None) – The permuation applied to the physical leg, which gets used to adjust state_labels and perm. If you sorted the previous leg with perm_qind, new_leg_charge = leg.sort(), use leg.perm_flat_from_perm_qind(perm_qind). Ignored if None.

property dim

Dimension of the local Hilbert space.

classmethod from_hdf5(hdf5_loader, h5gr, subpath)[source]

Load instance from a HDF5 file.

This method reconstructs a class instance from the data saved with save_hdf5().

Parameters
  • hdf5_loader (Hdf5Loader) – Instance of the loading engine.

  • h5gr (Group) – HDF5 group which is represent the object to be constructed.

  • subpath (str) – The name of h5gr with a '/' in the end.

Returns

obj – Newly generated class instance containing the required data.

Return type

cls

get_op(name)[source]

Return operator of given name.

Parameters

name (str) – The name of the operator to be returned. In case of multiple operator names separated by whitespace, we multiply them together to a single on-site operator (with the one on the right acting first).

Returns

op – The operator given by name, with labels 'p', 'p*'. If name already was an npc Array, it’s directly returned.

Return type

np_conserved

multiply_op_names(names)[source]

Multiply operator names together.

Join the operator names in names such that get_op returns the product of the corresponding operators.

Parameters

names (list of str) – List of valid operator labels.

Returns

combined_opname – A valid operator name Operatorname representing the product of operators in names.

Return type

str

property onsite_ops

Dictionary of on-site operators for iteration.

Single operators are accessible as attributes.

op_needs_JW(name)[source]

Whether an (composite) onsite operator is fermionic and needs a Jordan-Wigner string.

Parameters

name (str) – The name of the operator, as in get_op().

Returns

needs_JW – Whether the operator needs a Jordan-Wigner string, judging from need_JW_string.

Return type

bool

remove_op(name)[source]

Remove an added operator.

Parameters

name (str) – The name of the operator to be removed.

rename_op(old_name, new_name)[source]

Rename an added operator.

Parameters
  • old_name (str) – The old name of the operator.

  • new_name (str) – The new name of the operator.

save_hdf5(hdf5_saver, h5gr, subpath)[source]

Export self into a HDF5 file.

This method saves all the data it needs to reconstruct self with from_hdf5().

This implementation saves the content of __dict__ with save_dict_content(), storing the format under the attribute 'format'.

Parameters
  • hdf5_saver (Hdf5Saver) – Instance of the saving engine.

  • h5gr (:class`Group`) – HDF5 group which is supposed to represent self.

  • subpath (str) – The name of h5gr with a '/' in the end.

state_index(label)[source]

Return index of a basis state from its label.

Parameters

label (int | string) – eather the index directly or a label (string) set before.

Returns

state_index – the index of the basis state associated with the label.

Return type

int

state_indices(labels)[source]

Same as state_index(), but for multiple labels.

test_sanity()[source]

Sanity check, raises ValueErrors, if something is wrong.

valid_opname(name)[source]

Check whether ‘name’ labels a valid onsite-operator.

Parameters

name (str) – Label for the operator. Can be multiple operator(labels) separated by whitespace, indicating that they should be multiplied together.

Returns

validTrue if name is a valid argument to get_op().

Return type

bool