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")

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

>>> qcel.constants.conversion_factor("bohr", "miles")

Periodic Table Data

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

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

>>> qcel.periodictable.to_mass(10)

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": ...}


Getting Started


QCSchema Models

Implementation descriptions of QCSchema objects in Python.

Developer Documentation

Contains in-depth developer documentation and API references.

Indices and tables