pymatgen.analysis.chemenv.coordination_environments.coordination_geometry_finder module

This module contains the main object used to identify the coordination environments in a given structure. If you use this module, please cite the following: David Waroquiers, Xavier Gonze, Gian-Marco Rignanese, Cathrin Welker-Nieuwoudt, Frank Rosowski, Michael Goebel, Stephan Schenk, Peter Degelmann, Rute Andre, Robert Glaum, and Geoffroy Hautier, “Statistical analysis of coordination environments in oxides”, Chem. Mater., 2017, 29 (19), pp 8346–8360, DOI: 10.1021/acs.chemmater.7b02766

class AbstractGeometry(central_site=None, bare_coords=None, centering_type='standard', include_central_site_in_centroid=False, optimization=None)

Bases: object

Class used to describe a geometry (perfect or distorted)

Constructor for the abstract geometry :param central_site: Coordinates of the central site :param bare_coords: Coordinates of the neighbors of the central site :param centering_type: How to center the abstract geometry :param include_central_site_in_centroid: When the centering is on the centroid, the central site is included

if this parameter is set to True.

Raise

ValueError if the parameters are not consistent

property cn

Coordination number

Type

return

property coordination_number

Coordination number

Type

return

classmethod from_cg(cg, centering_type='standard', include_central_site_in_centroid=False)

Parameters

• cg –

• centering_type –

• include_central_site_in_centroid –

Returns

points_wcs_csc(permutation=None)

Parameters

permutation –

Returns

points_wcs_ctwcc(permutation=None)

Parameters

permutation –

Returns

points_wcs_ctwocc(permutation=None)

Parameters

permutation –

Returns

points_wocs_csc(permutation=None)

Parameters

permutation –

Returns

points_wocs_ctwcc(permutation=None)

Parameters

permutation –

Returns

points_wocs_ctwocc(permutation=None)

Parameters

permutation –

Returns

class LocalGeometryFinder(permutations_safe_override=False, plane_ordering_override=True, debug_level=None, plane_safe_permutations=False, only_symbols=None)

Bases: object

Main class used to find the local environments in a structure

Constructor for the LocalGeometryFinder, initializes the list of coordination geometries :param permutations_safe_override: If set to True, all permutations are tested (very time-consuming for large

coordination numbers!)

Parameters

plane_ordering_override – If set to False, the ordering of the points in the plane is disabled

BVA_DISTANCE_SCALE_FACTORS = {'GGA_relaxed': 1.015, 'LDA_relaxed': 0.995, 'experimental': 1.0}

DEFAULT_BVA_DISTANCE_SCALE_FACTOR = 1.0

DEFAULT_SPG_ANALYZER_OPTIONS = {'angle_tolerance': 5, 'symprec': 0.001}

DEFAULT_STRATEGY = <pymatgen.analysis.chemenv.coordination_environments.chemenv_strategies.MultiWeightsChemenvStrategy object>

PRESETS = {'DEFAULT': {'maximum_distance_factor': 2.0, 'minimum_angle_factor': 0.05, 'optimization': 2, 'voronoi_normalized_angle_tolerance': 0.03, 'voronoi_normalized_distance_tolerance': 0.05}}

STRUCTURE_REFINEMENT_NONE = 'none'

STRUCTURE_REFINEMENT_REFINED = 'refined'

STRUCTURE_REFINEMENT_SYMMETRIZED = 'symmetrized'

compute_coordination_environments(structure, indices=None, only_cations=True, strategy=<pymatgen.analysis.chemenv.coordination_environments.chemenv_strategies.MultiWeightsChemenvStrategy object>, valences='bond-valence-analysis', initial_structure_environments=None)

Parameters

• structure –

• indices –

• only_cations –

• strategy –

• valences –

• initial_structure_environments –

Returns

compute_structure_environments(excluded_atoms=None, only_atoms=None, only_cations=True, only_indices=None, maximum_distance_factor=2.0, minimum_angle_factor=0.05, max_cn=None, min_cn=None, only_symbols=None, valences='undefined', additional_conditions=None, info=None, timelimit=None, initial_structure_environments=None, get_from_hints=False, voronoi_normalized_distance_tolerance=0.05, voronoi_normalized_angle_tolerance=0.03, recompute=None, optimization=2)

Computes and returns the StructureEnvironments object containing all the information about the coordination environments in the structure :param excluded_atoms: Atoms for which the coordination geometries does not have to be identified :param only_atoms: If not set to None, atoms for which the coordination geometries have to be identified :param only_cations: If set to True, will only compute environments for cations :param only_indices: If not set to None, will only compute environments the atoms of the given indices :param maximum_distance_factor: If not set to None, neighbors beyond

maximum_distance_factor*closest_neighbor_distance are not considered

Parameters

• minimum_angle_factor – If not set to None, neighbors for which the angle is lower than minimum_angle_factor*largest_angle_neighbor are not considered

• max_cn – maximum coordination number to be considered

• min_cn – minimum coordination number to be considered

• only_symbols – if not set to None, consider only coordination environments with the given symbols

• valences – valences of the atoms

• additional_conditions – additional conditions to be considered in the bonds (example : only bonds between cation and anion

• info – additional info about the calculation

• timelimit – time limit (in secs) after which the calculation of the StructureEnvironments object stops

• initial_structure_environments – initial StructureEnvironments object (most probably incomplete)

• get_from_hints – whether to add neighbors sets from “hints” (e.g. capped environment => test the neighbors without the cap)

• voronoi_normalized_distance_tolerance – tolerance for the normalized distance used to distinguish neighbors sets

• voronoi_normalized_angle_tolerance – tolerance for the normalized angle used to distinguish neighbors sets

• recompute – whether to recompute the sites already computed (when initial_structure_environments is not None)

• optimization – optimization algorithm

Returns

The StructureEnvironments object containing all the information about the coordination environments in the structure

coordination_geometry_symmetry_measures(coordination_geometry, tested_permutations=False, points_perfect=None, optimization=None)

Returns the symmetry measures of a given coordination_geometry for a set of permutations depending on the permutation setup. Depending on the parameters of the LocalGeometryFinder and on the coordination

geometry, different methods are called.

Parameters

coordination_geometry – Coordination geometry for which the symmetry measures are looked for

Returns

the symmetry measures of a given coordination_geometry for a set of permutations

Raise

NotImplementedError if the permutation_setup does not exists

coordination_geometry_symmetry_measures_fallback_random(coordination_geometry, NRANDOM=10, points_perfect=None)

Returns the symmetry measures for a random set of permutations for the coordination geometry “coordination_geometry”. Fallback implementation for the plane separation algorithms measures of each permutation :param coordination_geometry: The coordination geometry to be investigated :param NRANDOM: Number of random permutations to be tested :return: The symmetry measures for the given coordination geometry for each permutation investigated

coordination_geometry_symmetry_measures_separation_plane(coordination_geometry, separation_plane_algo, testing=False, tested_permutations=False, points_perfect=None)

Returns the symmetry measures of the given coordination geometry “coordination_geometry” using separation facets to reduce the complexity of the system. Caller to the refined 2POINTS, 3POINTS and other … :param coordination_geometry: The coordination geometry to be investigated :return: The symmetry measures for the given coordination geometry for each plane and permutation investigated

coordination_geometry_symmetry_measures_separation_plane_optim(coordination_geometry, separation_plane_algo, points_perfect=None, nb_set=None, optimization=None)

Returns the symmetry measures of the given coordination geometry “coordination_geometry” using separation facets to reduce the complexity of the system. Caller to the refined 2POINTS, 3POINTS and other … :param coordination_geometry: The coordination geometry to be investigated. :param separation_plane_algo: Separation Plane algorithm used. :param points_perfect: Points corresponding to the perfect geometry. :param nb_set: Neighbor set for this set of points. (used to store already computed separation planes) :param optimization: Optimization level (1 or 2).

Returns

Continuous symmetry measures for the given coordination geometry for each plane and permutation

investigated, corresponding permutations, corresponding algorithms, corresponding mappings from local to perfect environment and corresponding mappings from perfect to local environment.

Return type

tuple

coordination_geometry_symmetry_measures_sepplane_optim(coordination_geometry, points_perfect=None, nb_set=None, optimization=None)

Returns the symmetry measures of a given coordination_geometry for a set of permutations depending on the permutation setup. Depending on the parameters of the LocalGeometryFinder and on the coordination

geometry, different methods are called.

Parameters

coordination_geometry – Coordination geometry for which the symmetry measures are looked for

Returns

the symmetry measures of a given coordination_geometry for a set of permutations

Raise

NotImplementedError if the permutation_setup does not exists

coordination_geometry_symmetry_measures_standard(coordination_geometry, algo, points_perfect=None, optimization=None)

Returns the symmetry measures for a set of permutations (whose setup depends on the coordination geometry) for the coordination geometry “coordination_geometry”. Standard implementation looking for the symmetry measures of each permutation :param coordination_geometry: The coordination geometry to be investigated :return: The symmetry measures for the given coordination geometry for each permutation investigated

get_coordination_symmetry_measures(only_minimum=True, all_csms=True, optimization=None)

Returns the continuous symmetry measures of the current local geometry in a dictionary. :return: the continuous symmetry measures of the current local geometry in a dictionary.

get_coordination_symmetry_measures_optim(only_minimum=True, all_csms=True, nb_set=None, optimization=None)

Returns the continuous symmetry measures of the current local geometry in a dictionary. :return: the continuous symmetry measures of the current local geometry in a dictionary.

get_structure()

Returns the pymatgen Structure that has been setup for the identification of geometries (the initial one might have been refined/symmetrized using the SpaceGroupAnalyzer). :return: The pymatgen Structure that has been setup for the identification of geometries (the initial one might have been refined/symmetrized using the SpaceGroupAnalyzer).

set_structure(lattice, species, coords, coords_are_cartesian)

Sets up the pymatgen structure for which the coordination geometries have to be identified starting from the lattice, the species and the coordinates :param lattice: The lattice of the structure :param species: The species on the sites :param coords: The coordinates of the sites :param coords_are_cartesian: If set to True, the coordinates are given in cartesian coordinates

setup_explicit_indices_local_geometry(explicit_indices)

Sets up explicit indices for the local geometry, for testing purposes :param explicit_indices: explicit indices for the neighbors (set of numbers from 0 to CN-1 in a given order)

setup_local_geometry(isite, coords, optimization=None)

Sets up the AbstractGeometry for the local geometry of site with index isite. :param isite: Index of the site for which the local geometry has to be set up :param coords: The coordinates of the (local) neighbors

setup_ordered_indices_local_geometry(coordination)

Sets up ordered indices for the local geometry, for testing purposes :param coordination: coordination of the local geometry

setup_parameter(parameter, value)

Setup of one specific parameter to the given value. The other parameters are unchanged. See setup_parameters method for the list of possible parameters :param parameter: Parameter to setup/update :param value: Value of the parameter

setup_parameters(centering_type='standard', include_central_site_in_centroid=False, bva_distance_scale_factor=None, structure_refinement='refined', spg_analyzer_options=None)

Setup of the parameters for the coordination geometry finder. A reference point for the geometries has to be chosen. This can be the centroid of the structure (including or excluding the atom for which the coordination geometry is looked for) or the atom itself. In the ‘standard’ centering_type, the reference point is the central atom for coordination numbers 1, 2, 3 and 4 and the centroid for coordination numbers > 4. :param centering_type: Type of the reference point (centering) ‘standard’, ‘centroid’ or ‘central_site’ :param include_central_site_in_centroid: In case centering_type is ‘centroid’, the central site is included if

this value is set to True.

Parameters

• bva_distance_scale_factor – Scaling factor for the bond valence analyzer (this might be different whether the structure is an experimental one, an LDA or a GGA relaxed one, or any other relaxation scheme (where under- or over-estimation of bond lengths is known).

• structure_refinement – Refinement of the structure. Can be “none”, “refined” or “symmetrized”.

• spg_analyzer_options – Options for the SpaceGroupAnalyzer (dictionary specifying “symprec” and “angle_tolerance”. See pymatgen’s SpaceGroupAnalyzer for more information.

setup_random_indices_local_geometry(coordination)

Sets up random indices for the local geometry, for testing purposes :param coordination: coordination of the local geometry

setup_random_structure(coordination)

Sets up a purely random structure with a given coordination. :param coordination: coordination number for the random structure

setup_structure(structure)

Sets up the structure for which the coordination geometries have to be identified. The structure is analyzed with the space group analyzer and a refined structure is used :param structure: A pymatgen Structure

setup_test_perfect_environment(symbol, randomness=False, max_random_dist=0.1, symbol_type='mp_symbol', indices='RANDOM', random_translation='NONE', random_rotation='NONE', random_scale='NONE', points=None)

Parameters

• symbol –

• randomness –

• max_random_dist –

• symbol_type –

• indices –

• random_translation –

• random_rotation –

• random_scale –

• points –

Returns

update_nb_set_environments(se, isite, cn, inb_set, nb_set, recompute=False, optimization=None)

Parameters

• se –

• isite –

• cn –

• inb_set –

• nb_set –

• recompute –

• optimization –

Returns

find_rotation(points_distorted, points_perfect)

This finds the rotation matrix that aligns the (distorted) set of points “points_distorted” with respect to the (perfect) set of points “points_perfect” in a least-square sense. :param points_distorted: List of points describing a given (distorted) polyhedron for which the rotation that

aligns these points in a least-square sense to the set of perfect points “points_perfect”

Parameters

points_perfect – List of “perfect” points describing a given model polyhedron.

Returns

The rotation matrix

find_scaling_factor(points_distorted, points_perfect, rot)

This finds the scaling factor between the (distorted) set of points “points_distorted” and the (perfect) set of points “points_perfect” in a least-square sense. :param points_distorted: List of points describing a given (distorted) polyhedron for which the scaling factor has

to be obtained.

Parameters

• points_perfect – List of “perfect” points describing a given model polyhedron.

• rot – The rotation matrix

Returns

The scaling factor between the two structures and the rotated set of (distorted) points.

symmetry_measure(points_distorted, points_perfect)

Computes the continuous symmetry measure of the (distorted) set of points “points_distorted” with respect to the (perfect) set of points “points_perfect”. :param points_distorted: List of points describing a given (distorted) polyhedron for which the symmetry measure

has to be computed with respect to the model polyhedron described by the list of points “points_perfect”.

Parameters

points_perfect – List of “perfect” points describing a given model polyhedron.

Returns

The continuous symmetry measure of the distorted polyhedron with respect to the perfect polyhedron