ChargeInfo

• full name: tenpy.linalg.charges.ChargeInfo

• parent module: tenpy.linalg.charges

• type: class

Inheritance Diagram

Methods

ChargeInfo.__init__([mod, names])
ChargeInfo.add(chinfos)	Create a ChargeInfo combining multiple charges.
ChargeInfo.change(chinfo, charge, new_qmod)	Change the qmod of a given charge.
ChargeInfo.check_valid(charges)	Check, if charges has all entries as expected from self.mod.
ChargeInfo.drop(chinfo[, charge])	Remove a charge from a ChargeInfo.
ChargeInfo.from_hdf5(hdf5_loader, h5gr, subpath)	Load instance from a HDF5 file.
ChargeInfo.make_valid([charges])	Take charges modulo self.mod.
ChargeInfo.save_hdf5(hdf5_saver, h5gr, subpath)	Export self into a HDF5 file.
ChargeInfo.test_sanity()	Sanity check, raises ValueErrors, if something is wrong.

Class Attributes and Properties

ChargeInfo.mod	Modulo how much each of the charges is taken.
ChargeInfo.qnumber	The number of charges.

class tenpy.linalg.charges.ChargeInfo(mod=[], names=None)

Bases: object

Meta-data about the charge of a tensor.

Saves info about the nature of the charge of a tensor. Provides make_valid() for taking modulo m.

(This class is implemented in tenpy.linalg.charges but also imported in tenpy.linalg.np_conserved for convenience.)

Parameters:

• mod (iterable of QTYPE) – The len gives the number of charges, qnumber. Each entry is a positive integer, where 1 implies a \(U(1)\) charge and N>1 implies a \(Z_N\) symmetry. Defaults to “trivial”, i.e., no charge.

• names (list of str) – Descriptive names for the charges. Defaults to ['']*qnumber.

names

A descriptive name for each of the charges. May have ‘’ entries.

Type:

list of strings

_mask

mask (mod == 1), to speed up make_valid in pure python.

Type:

1D array bool

_mod_masked

Equivalent to self.mod[self._mask]

Type:

1D array QTYPE

_qnumber, _mod

Storage of qnumber and mod.

Notes

Instances of this class can (should) be shared between different LegCharge and Array’s.

save_hdf5(hdf5_saver, h5gr, subpath)

Export self into a HDF5 file.

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

It stores the names under the path "names", and mod as dataset "U1_ZN".

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.

classmethod from_hdf5(hdf5_loader, h5gr, subpath)

Load instance from a HDF5 file.

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

The "U1_ZN" dataset is mandatory, 'names' are optional.

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

classmethod add(chinfos)

Create a ChargeInfo combining multiple charges.

Parameters:

chinfos (iterable of ChargeInfo) – ChargeInfo instances to be combined into a single one (in the given order).

Returns:

chinfo – ChargeInfo combining all the given charges.

Return type:

ChargeInfo

classmethod drop(chinfo, charge=None)

Remove a charge from a ChargeInfo.

Parameters:

• chinfo (ChargeInfo) – The ChargeInfo from where to drop/remove a charge.

• charge (int | str) – Number or name of the charge (within chinfo) which is to be dropped. None means dropping all charges.

Returns:

chinfo – ChargeInfo where the specified charge is dropped.

Return type:

ChargeInfo

classmethod change(chinfo, charge, new_qmod, new_name='')

Change the qmod of a given charge.

Parameters:

• chinfo (ChargeInfo) – The ChargeInfo for which qmod of charge should be changed.

• new_qmod (int) – The new qmod to be set.

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

Returns:

chinfo – ChargeInfo where qmod of the specified charge was changed.

Return type:

ChargeInfo

test_sanity()

Sanity check, raises ValueErrors, if something is wrong.

property qnumber

The number of charges.

property mod

Modulo how much each of the charges is taken.

Entries are 1 for a \(U(1)\) charge, and N for a \(Z_N\) symmetry.

make_valid(charges=None)

Take charges modulo self.mod.

Parameters:

charges (array_like or None) – 1D or 2D array of charges, last dimension self.qnumber None defaults to trivial charges np.zeros(qnumber, dtype=QTYPE).

Returns:

A copy of charges taken modulo mod, but with x % 1 := x

Return type:

charges

check_valid(charges)

Check, if charges has all entries as expected from self.mod.

Parameters:

charges (2D ndarray QTYPE_t) – Charge values to be checked.

Returns:

res – True, if all 0 <= charges <= self.mod (wherever self.mod != 1)

Return type:

bool