index.rst

QCElemental

QCElemental is a resource module for quantum chemistry containing physical constants and periodic table data from NIST and molecule handlers.

Physical Constants

Physical constants can be acquired directly from the NIST CODATA:

>>> qcel.constants.get("hartree energy in ev")
27.21138602

Alternatively, with the use of the Pint unit conversion package, arbitrary conversion factors can be obtained:

>>> qcel.constants.conversion_factor("bohr", "miles")
3.2881547429884475e-14

Periodic Table Data

A variety of periodic table quantities are available using virtually any alias:

>>> qcel.periodictable.to_mass("Ne")
19.9924401762

>>> qcel.periodictable.to_mass(10)
19.9924401762

Molecule Handlers

Molecules can be translated to/from the MolSSI QCSchema format or quantum chemistry program specific input specifications such as NWChem, Psi4, and CFour. In addition, databases such as PubChem can be searched:

>>> qcel.molparse.from_string("pubchem:benzene")
    Searching PubChem database for benzene (single best match returned)
    Found 1 result(s)
    {"geometry": ...}

---

Index

Getting Started

• :doc:`install`

.. toctree::
   :maxdepth: 1
   :hidden:
   :caption: Getting Started

   install

Quantities

• :doc:`physconst`
• :doc:`periodic_table`
• :doc:`covalent_radii`
• :doc:`vanderwaals_radii`

.. toctree::
   :maxdepth: 1
   :hidden:
   :caption: Quantities

   physconst
   periodic_table
   covalent_radii
   vanderwaals_radii

QCSchema Models

Implementation descriptions of QCSchema objects in Python.

• :doc:`models`
• :doc:`model_molecule`
• :doc:`model_result`
• :doc:`model_common`

.. toctree::
   :maxdepth: 1
   :hidden:
   :caption: QCSchema Models

   models
   model_molecule
   model_result
   model_common

Developer Documentation

Contains in-depth developer documentation and API references.

• :doc:`api`
• :doc:`changelog`

.. toctree::
   :maxdepth: 2
   :caption: Developer Documentation
   :hidden:

   api
   changelog

Indices and tables

• :ref:`genindex`
• :ref:`modindex`
• :ref:`search`