Cluster space

class hiphive.ClusterSpace(prototype_structure, cutoffs, sum_rules=True, symprec=1e-05, length_scale=0.1)[source]

Primitive object handling cluster and force constants for a structure.

  • prototype_struture (ASE Atoms object) – prototype structure; spglib will be used to find a suitable cell based on this structure.
  • cutoffs (list) – cutoff radii for different orders starting with second order
  • sum_rules (bool) – If True the aucostic sum rules will be enforced by constraining the parameters.
  • symprec (float) – numerical precision that will be used for analyzing the symmetry (this parameter will be forwarded to spglib)
  • length_scale (float) – This will be used as a normalization constant for the eigentensors


To instantiate a ClusterSpace object one has to specify a prototype structure and cutoff radii for each cluster order that should be included. For example the following snippet will set up a ClusterSpace object for a BCC structure including second order terms up to a distance of 5 A and third order terms up to a distance of 4 A.

>>> from import bulk
>>> prim = bulk('W')
>>> cs = ClusterSpace(prim, [5.0, 4.0])

AtomList – The atoms within the cutoff from the center cell


ClusterList – Contains the clusters possible within the cutoff


Cutoffs obj – The cutoffs used for construcring the cluster space

get_sum_rule_constraint_matrices(symbolic=True, rotational=False)[source]

Return the constraint matrices needed for imposing the (acoustic=translational) sum rule.

Returns:dictionary of constraint matrices, where the key is the order of the respective constraint matrix
Return type:dict

float – The normalization of the force constants


int – The number of free parameters in the model

If the sum rules are not enforced the number of DOF is the same as the total number of eigentensors in all orbits


list – list of dictionaries containing detailed information for each orbit, e.g. cluster radius and atom types.


list of Orbit objects – The orbits of the structure


list of vectors – lookup for permutation references


Atoms – the structure of the lattice


Prints a list of all orbits.


Load a ClusterSpace instance from file

Parameters:f (string or file object) – name of input file (string) or stream to load from (file object)

list of 3x3 matrices – The rotation for each symmetry


str – The space group of the lattice obtained from spglib


bool – whether the sum rules are enforced


float – The symprec value used when constructing the cluster space


list of 3-vectors – the translation for each symmetry


Saves to file or to a file-like object

The instance is saved into a custom format based on tar-files. The resulting file will be a valid tar file and can be browsed by by a tar reader. The included objects are themself either pickles, npz or other tars.

Parameters:fileobj (str or file-like obj) – If the input is a string a tar archive will be created in the current directory. If not a string the input must be a valid file like obj.

The wyckoff sites in the primitive cell