
.. _`sec:psithonFunc`:

=========================================
Psithon Functions: Invoking a Calculation
=========================================

To allow arbitrarily complex computations to be performed, |PSIfour| is built
upon the Python interpreter, with modifications termed Psithon. Sec. 
:ref:`sec:psithonInput` describes the non-standard Python associated with
clean molecule, basis, and option specification in the |PSIfour| input file.
This documentation addresses the pure Python side- what functions allow
the efficient compiled code to be run, what functions post-process and
interact with that output, and how the ordinary (or ambitious) user can
extent |PSIfours| functionality.

.. toctree::
   :maxdepth: 2

   notes_py
   energy
   prop
   cp
   opt
   freq
   db
   cbs
   diatomic
   intercalls
   sowreap
   cubeprop

