Cremer-Pople total puckering amplitude Q
========================================

Cremer-Pople parameters are valuable for the description of ring-puckering. For a 6-membered ring
system, for example, three parameters are needed that are implemented in the :mod:`metafalcon`
package. For the calculation of Cremer-Pople parameters, it is necessary to specify the atoms
:math:`i,j,k,l,m,n` that define the ring-system.

The use of the total puckering amplitude Q is invoked by the following block in the
`meta-config.json` file::

    "collective variables": [
      {
        "type": "cremerpople_q",
        "name": "total puckering amplitude Q",
        "atoms": [i, j, k, l, m, n]
      },
      ...
    ]

Apart from type and name, only the indices of the contributing ``"atoms"`` are needed.

.. note::
    Since Cremer-Pople parameters depend on the atom ordering, it is necessary to ensure the
    correct ordering in the ``"atoms"`` list.