.. auto-generated by dev_tools.docs.nxdl from the NXDL source base_classes/NXunit_cell.nxdl.xml -- DO NOT EDIT

.. index::
    ! NXunit_cell (base class)
    ! unit_cell (base class)
    see: unit_cell (base class); NXunit_cell

.. _NXunit_cell:

===========
NXunit_cell
===========

**Status**:

  base class, extends :ref:`NXobject`

**Description**:

  .. collapse:: Base class to describe structural aspects of an arrangement of ...

      Base class to describe structural aspects of an arrangement of
      atoms or ions including a crystallographic unit cell.

      Following recommendations of `CIF <https://www.iucr.org/resources/cif/spec/version1.1>`_ and `International Tables of Crystallography <https://it.iucr.org/>`_.

**Symbols**:


  **d**: Dimensionality of the lattice.

**Groups cited**:
  :ref:`NXatom`

.. index:: NXatom (base class); used in base class

**Structure**:

  .. _/NXunit_cell/reference_frame-field:

  .. index:: reference_frame (field)

  **reference_frame**: (optional) :ref:`NX_CHAR <NX_CHAR>` 

    .. collapse:: Path to a reference frame in which the unit cell is defined ...

        Path to a reference frame in which the unit cell is defined
        to resolve ambiguity in cases when e.g. a different reference frame
        than the NeXus default reference frame (McStas) was chosen.

  .. _/NXunit_cell/dimensionality-field:

  .. index:: dimensionality (field)

  **dimensionality**: (optional) :ref:`NX_POSINT <NX_POSINT>` 

    .. collapse:: Dimensionality of the structure. ...

        Dimensionality of the structure.

        Any of these values: ``1`` | ``2`` | ``3``

  .. _/NXunit_cell/a_b_c-field:

  .. index:: a_b_c (field)

  **a_b_c**: (optional) :ref:`NX_NUMBER <NX_NUMBER>` (Rank: 1, Dimensions: [d]) {units=\ :ref:`NX_LENGTH <NX_LENGTH>`} 

    Geometry of the unit cell quantified via parameters a, b, and c.

  .. _/NXunit_cell/a-field:

  .. index:: a (field)

  **a**: (optional) :ref:`NX_NUMBER <NX_NUMBER>` {units=\ :ref:`NX_LENGTH <NX_LENGTH>`} 

    Geometry of the unit cell quantified individually via parameter a.

  .. _/NXunit_cell/b-field:

  .. index:: b (field)

  **b**: (optional) :ref:`NX_NUMBER <NX_NUMBER>` {units=\ :ref:`NX_LENGTH <NX_LENGTH>`} 

    Geometry of the unit cell quantified individually via parameter b.

  .. _/NXunit_cell/c-field:

  .. index:: c (field)

  **c**: (optional) :ref:`NX_NUMBER <NX_NUMBER>` {units=\ :ref:`NX_LENGTH <NX_LENGTH>`} 

    Geometry of the unit cell quantified individually via parameter c.

  .. _/NXunit_cell/alpha_beta_gamma-field:

  .. index:: alpha_beta_gamma (field)

  **alpha_beta_gamma**: (optional) :ref:`NX_NUMBER <NX_NUMBER>` (Rank: 1, Dimensions: [d]) {units=\ :ref:`NX_ANGLE <NX_ANGLE>`} 

    Geometry of the unit cell quantified via parameters alpha, beta, and gamma.

  .. _/NXunit_cell/alpha-field:

  .. index:: alpha (field)

  **alpha**: (optional) :ref:`NX_NUMBER <NX_NUMBER>` {units=\ :ref:`NX_ANGLE <NX_ANGLE>`} 

    Geometry of the unit cell quantified individually via parameter alpha.

  .. _/NXunit_cell/beta-field:

  .. index:: beta (field)

  **beta**: (optional) :ref:`NX_NUMBER <NX_NUMBER>` {units=\ :ref:`NX_ANGLE <NX_ANGLE>`} 

    Geometry of the unit cell quantified individually via parameter beta.

  .. _/NXunit_cell/gamma-field:

  .. index:: gamma (field)

  **gamma**: (optional) :ref:`NX_NUMBER <NX_NUMBER>` {units=\ :ref:`NX_ANGLE <NX_ANGLE>`} 

    Geometry of the unit cell quantified individually via parameter gamma.

  .. _/NXunit_cell/crystal_system-field:

  .. index:: crystal_system (field)

  **crystal_system**: (optional) :ref:`NX_CHAR <NX_CHAR>` 

    .. collapse:: Crystal system. ...

        Crystal system.

        For a crystal system in 2D space monoclinic is an exact synonym for oblique.
        For a crystal system in 2D space orthorhombic is an exact synonym for rectangular.
        For a crystal system in 2D space tetragonal is an exact synonym for square.

        Any of these values:

          * ``triclinic``

          * ``monoclinic``

          * ``orthorhombic``

          * ``tetragonal``

          * ``rhombohedral``

          * ``hexagonal``

          * ``cubic``


  .. _/NXunit_cell/laue_group-field:

  .. index:: laue_group (field)

  **laue_group**: (optional) :ref:`NX_CHAR <NX_CHAR>` 

    Laue group using International Table of Crystallography notation.

  .. _/NXunit_cell/point_group-field:

  .. index:: point_group (field)

  **point_group**: (optional) :ref:`NX_CHAR <NX_CHAR>` 

    Point group using International Table of Crystallography notation.

  .. _/NXunit_cell/space_group-field:

  .. index:: space_group (field)

  **space_group**: (optional) :ref:`NX_CHAR <NX_CHAR>` 

    Space group from the International Table of Crystallography notation.

  .. _/NXunit_cell/is_centrosymmetric-field:

  .. index:: is_centrosymmetric (field)

  **is_centrosymmetric**: (optional) :ref:`NX_BOOLEAN <NX_BOOLEAN>` 

    .. collapse:: True if space group is considered a centrosymmetric one. ...

        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).

  .. _/NXunit_cell/is_chiral-field:

  .. index:: is_chiral (field)

  **is_chiral**: (optional) :ref:`NX_BOOLEAN <NX_BOOLEAN>` 

    .. collapse:: True if space group is considered a chiral one. ...

        True if space group is considered a chiral one.
        False if space group is consider a non-chiral one.

  .. _/NXunit_cell/area-field:

  .. index:: area (field)

  **area**: (optional) :ref:`NX_NUMBER <NX_NUMBER>` {units=\ :ref:`NX_AREA <NX_AREA>`} 

    Area of the unit cell if dimensionality is 2.

  .. _/NXunit_cell/volume-field:

  .. index:: volume (field)

  **volume**: (optional) :ref:`NX_NUMBER <NX_NUMBER>` {units=\ :ref:`NX_VOLUME <NX_VOLUME>`} 

    Volume of the unit cell if dimensionality is 3.

  .. _/NXunit_cell/ATOM-group:

  :bolditalic:`ATOM`: (optional) :ref:`NXatom` 



Hypertext Anchors
-----------------

List of hypertext anchors for all groups, fields,
attributes, and links defined in this class.


* :ref:`/NXunit_cell/a-field </NXunit_cell/a-field>`
* :ref:`/NXunit_cell/a_b_c-field </NXunit_cell/a_b_c-field>`
* :ref:`/NXunit_cell/alpha-field </NXunit_cell/alpha-field>`
* :ref:`/NXunit_cell/alpha_beta_gamma-field </NXunit_cell/alpha_beta_gamma-field>`
* :ref:`/NXunit_cell/area-field </NXunit_cell/area-field>`
* :ref:`/NXunit_cell/ATOM-group </NXunit_cell/ATOM-group>`
* :ref:`/NXunit_cell/b-field </NXunit_cell/b-field>`
* :ref:`/NXunit_cell/beta-field </NXunit_cell/beta-field>`
* :ref:`/NXunit_cell/c-field </NXunit_cell/c-field>`
* :ref:`/NXunit_cell/crystal_system-field </NXunit_cell/crystal_system-field>`
* :ref:`/NXunit_cell/dimensionality-field </NXunit_cell/dimensionality-field>`
* :ref:`/NXunit_cell/gamma-field </NXunit_cell/gamma-field>`
* :ref:`/NXunit_cell/is_centrosymmetric-field </NXunit_cell/is_centrosymmetric-field>`
* :ref:`/NXunit_cell/is_chiral-field </NXunit_cell/is_chiral-field>`
* :ref:`/NXunit_cell/laue_group-field </NXunit_cell/laue_group-field>`
* :ref:`/NXunit_cell/point_group-field </NXunit_cell/point_group-field>`
* :ref:`/NXunit_cell/reference_frame-field </NXunit_cell/reference_frame-field>`
* :ref:`/NXunit_cell/space_group-field </NXunit_cell/space_group-field>`
* :ref:`/NXunit_cell/volume-field </NXunit_cell/volume-field>`

**NXDL Source**:
  https://github.com/FAIRmat-NFDI/nexus_definitions/tree/fairmat/base_classes/NXunit_cell.nxdl.xml