httk.atomistic.models.formula.api
=================================

.. py:module:: httk.atomistic.models.formula.api

.. autoapi-nested-parse::

   The minimal canonical chemical-formula interface for httk-atomistic.



Classes
-------

.. autoapisummary::

   httk.atomistic.models.formula.api.ChemicalFormulaAPI


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

.. py:class:: ChemicalFormulaAPI

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


   Abstract base class for the canonical chemical-formula interface.

   The concrete defaults keep backends that do not have provenance for optional
   formula metadata interoperable without requiring them to implement every accessor.


   .. py:property:: amounts
      :type: tuple[tuple[str, fractions.Fraction], Ellipsis]

      :abstractmethod:


      Ordered ``(label, exact amount)`` pairs for this chemical formula.

      Labels are element symbols in alphabetical order unless ``is_anonymous``, in
      which case they are OPTIMADE anonymous symbols in canonical
      (descending-coefficient) order.


   .. py:property:: is_anonymous
      :type: bool


      Whether the formula labels are OPTIMADE anonymous symbols.

      A backend that carries anonymous notation overrides this; a backend without
      that distinction inherits ``False``.


   .. py:property:: uncertainties
      :type: tuple[tuple[str, fractions.Fraction | None], Ellipsis]


      Per-amount absolute uncertainties, or ``None`` where exactness is unstated.


   .. py:property:: complete
      :type: bool


      Whether the formula accounts for all represented elemental material.


   .. py:property:: exact
      :type: bool


      Whether all formula amounts are exact rather than precision-bounded.


   .. py:property:: normalized
      :type: bool


      Whether the formula is normalized within the stated precision.


   .. py:property:: normalization_status
      :type: str


      The formula's normalization status derived from exactness and normalization.


   .. py:property:: diagnostics
      :type: tuple[httk.atomistic.models.formula.diagnostics.CompositionDiagnostic, Ellipsis]


      Non-fatal structured diagnostics associated with the formula.