httk.atomistic.cell_api
=======================

.. py:module:: httk.atomistic.cell_api

.. autoapi-nested-parse::

   The minimal canonical cell interface for httk-atomistic.



Classes
-------

.. autoapisummary::

   httk.atomistic.cell_api.CellAPI


Module Contents
---------------

.. py:class:: CellAPI

   Bases: :py:obj:`abc.ABC`


   Abstract base class for the canonical cell interface.

   It declares the exact accessors that every cell backend produces from its own native
   representation and every cell view builds its presentation from: the ``basis`` of 3x3 lattice
   vectors (``scale * unscaled_basis``), the positive ``scale``, and the ``unscaled_basis``. All
   three are exact httk-core vectors; this is the single interchange format, with no pairwise
   conversion between backends.


   .. py:property:: basis
      :type: httk.core.SurdVector

      :abstractmethod:



   .. py:property:: scale
      :type: httk.core.SurdScalar

      :abstractmethod:



   .. py:property:: unscaled_basis
      :type: httk.core.SurdVector

      :abstractmethod:



   .. py:property:: precision
      :type: fractions.Fraction | None


      How precisely the basis was stated, as an absolute length, or ``None`` if unknown.

      A backend that knows its source's precision overrides this; one that does not — a
      bare matrix of numbers with no provenance — inherits ``None``.


   .. py:property:: periodicity
      :type: tuple[bool, bool, bool]


      Which of the three basis rows is a genuine lattice translation.

      A backend that knows its periodicity overrides this; one that does not inherit
      ``(True, True, True)``. A cell described only by six lattice parameters or a bare
      matrix is interpreted as a fully periodic crystal.