*******
DL_POLY
*******

.. py:class:: DL_POLY

This interface supports energy and gradient evaluations with the open source
`DL_POLY 5 <https://www.scd.stfc.ac.uk/Pages/DL_POLY.aspx>`_ molecular simulation package

A DL_POLY :ref:`Theory <theories>` object can be specified as follows::

  my_theory = DL_POLY(frag=..., ff='...', ...)

which would then be called as ``theory=my_theory`` in subsequent tasks.


General options
===============

.. py:attribute:: berendsen

   (default: ``(0.5,1.5)``)

.. py:attribute:: delr

   (default: ``0.0``)

.. py:attribute:: densvar

   (default: ``20``)

.. py:attribute:: dl_field_charges

   (default: ``True``) Allows DL_FIELD to overwrite the atomic charges

.. py:attribute:: dl_field_types

   (default: ``True``) Allows DL_FIELD to overwrite the atomic forcefield types

.. py:attribute:: equilibration

   (default: ``10``)

.. py:attribute:: ewald

   (default: ``1.E-6``)

.. py:attribute:: input
   :noindex:

   (default: ``('CONTROL','CONFIG','FIELD')``)

.. py:attribute:: output
   :noindex:

   (default: ``'_dl_poly.out'``)

.. py:attribute:: potential

   (default: ``False``)

.. py:attribute:: print

   (default: ``2``)

.. py:attribute:: rcut

   (default: ``-1.0``)

.. py:attribute:: rpad

   (default: ``0.0``)

.. py:attribute:: rvdw

   (default: ``0.0``)

.. py:attribute:: scale

   (default: ``2``)

.. py:attribute:: steps

   (default: ``20``)

.. py:attribute:: stack

   (default: ``50``)

.. py:attribute:: stats

   (default: ``2``)

.. py:attribute:: restart
   :noindex:

   (default: ``'scale'``)

.. py:attribute:: timestep

   (default: ``0.000``)


Importing biomolecular forcefields
==================================

CHARMM forcefields may be imported via the DL_FIELD package (see P450 tutorial).

AMBER forcefields in the `PRMTOP <https://ambermd.org/prmtop.pdf>`_ format can be imported
directly with ChemShell and do not need the help of DL_FIELD, for example::

  my_mm = DL_POLY(ff='MY_PRMTOP.top')

.. note:: An example of importing AMBER forcefields for QM/MM calculations
 can be found in the test suite 
 (``tests/qmmm/mndo-dl_poly/chorismate_mutase.py``)