NXem_ebsd_crystal_structure_model¶
Status:
base class, extends NXobject
Description:
Crystal structure phase models used for indexing Kikuchi pattern.
This base class contains key metadata relevant to every physical kinematic or dynamic diffraction model to be used for simulating Kikuchi diffraction pattern. The actual indexing of Kikuchi pattern however maybe use different algorithms which build on these simulation results but evaluate different workflows of comparing simulated and measured Kikuchi pattern to make suggestions which orientation is the most likely (if any) for each scan point investigated.
Traditionally Hough transform based indexing has been the most frequently used algorithm. More and more dictionary based alternatives are used. Either way both algorithm need a crystal structure model.
Symbols:
n_hkl: Number of reflectors (Miller crystallographic plane triplets).
n_pos: Number of atom positions.
- Groups cited:
none
Structure:
crystallographic_database_identifier: (optional) NX_CHAR
Identifier of an entry from crystallographic_database which was used for creating this structure model.
crystallographic_database: (optional) NX_CHAR
Name of the crystallographic database to resolve crystallographic_database_identifier e.g. COD or others.
unit_cell_abc: (optional) NX_FLOAT (Rank: 1, Dimensions: [3]) {units=NX_LENGTH}
Crystallography unit cell parameters a, b, and c.
unit_cell_alphabetagamma: (optional) NX_FLOAT (Rank: 1, Dimensions: [3]) {units=NX_ANGLE}
Crystallography unit cell parameters alpha, beta, and gamma.
unit_cell_volume: (optional) NX_FLOAT {units=NX_VOLUME}
Volume of the unit cell
space_group: (optional) NX_CHAR
Crystallographic space group
is_centrosymmetric: (optional) NX_BOOLEAN
True if space group is considered a centrosymmetric one. False if space group is considered a non-centrosymmetric one. Centrosymmetric has all types and combinations of symmetry elements (translation, rotational axis, mirror planes, center of inversion) Non-centrosymmetric compared to centrosymmetric is constrained (no inversion). Chiral compared to non-centrosymmetric is constrained (no mirror planes).
is_chiral: (optional) NX_BOOLEAN
True if space group is considered a chiral one. False if space group is consider a non-chiral one.
laue_group: (optional) NX_CHAR
Laue group
point_group: (optional) NX_CHAR
Point group using International Notation.
unit_cell_class: (optional) NX_CHAR
Crystal system
Any of these values:
triclinic
monoclinic
orthorhombic
tetragonal
rhombohedral
hexagonal
cubicphase_identifier: (optional) NX_UINT {units=NX_UNITLESS}
Numeric identifier for each phase. The value 0 is reserved for the unknown phase essentially representing the null-model that no phase model was sufficiently significantly confirmed. Consequently, the value 0 must not be used as a phase_identifier.
phase_name: (optional) NX_CHAR
Name of the phase/alias.
atom_identifier: (optional) NX_CHAR (Rank: 1, Dimensions: [n_pos])
Labels for each atom position
atom: (optional) NX_UINT (Rank: 1, Dimensions: [n_pos]) {units=NX_UNITLESS}
The hash value \(H\) is \(H = Z + N*256\) with \(Z\) the number of protons and \(N\) the number of neutrons of each isotope respectively. Z and N have to be 8-bit unsigned integers. For the rationale behind this M. Kühbach et al. (2021)
atom_positions: (optional) NX_FLOAT (Rank: 2, Dimensions: [n_pos, 3]) {units=NX_LENGTH}
Atom positions x, y, z.
atom_occupancy: (optional) NX_FLOAT (Rank: 1, Dimensions: [n_pos]) {units=NX_DIMENSIONLESS}
Relative occupancy of the atom position.
number_of_planes: (optional) NX_UINT {units=NX_UNITLESS}
How many reflectors are distinguished. Value has to be n_hkl.
plane_miller: (optional) NX_NUMBER (Rank: 2, Dimensions: [n_hkl, 3]) {units=NX_UNITLESS}
Miller indices \((hkl)\).
dspacing: (optional) NX_FLOAT (Rank: 1, Dimensions: [n_hkl]) {units=NX_LENGTH}
D-spacing.
relative_intensity: (optional) NX_FLOAT (Rank: 1, Dimensions: [n_hkl]) {units=NX_DIMENSIONLESS}
Relative intensity of the signal for the plane.
Hypertext Anchors¶
List of hypertext anchors for all groups, fields, attributes, and links defined in this class.
