Release History
===============

Releases follow the ``major.minor.micro`` scheme recommended by `PEP440 <https://www.python.org/dev/peps/pep-0440/#final-releases>`_, where

* ``major`` increments denote a change that may break API compatibility with previous ``major`` releases
* ``minor`` increments add features but do not break API compatibility
* ``micro`` increments represent bugfix releases or improvements in documentation

0.3.0 - API Improvements
------------------------

Several improvements and changes to public API.

New features
""""""""""""

* `PR #292 <https://github.com/openforcefield/openforcefield/pull/292>`_: Implement ``Topology.to_openmm`` and remove ``ToolkitRegistry.toolkit_is_available``
* `PR #322 <https://github.com/openforcefield/openforcefield/pull/322>`_: Install directories for the lookup of OFFXML files through the entry point group ``openforcefield.smirnoff_forcefield_directory``. The ``ForceField`` class doesn't search in the ``data/forcefield/`` folder anymore (now renamed ``data/test_forcefields/``), but only in ``data/``.

API-breaking Changes
""""""""""""""""""""
* `PR #278 <https://github.com/openforcefield/openforcefield/pull/278>`_: Standardize variable/method names
* `PR #291 <https://github.com/openforcefield/openforcefield/pull/291>`_: Remove ``ForceField.load/to_smirnoff_data``, add ``ForceField.to_file/string`` and ``ParameterHandler.add_parameters``. Change behavior of ``ForceField.register_X_handler`` functions.

Bugfixes
"""""""" 
* `PR #327 <https://github.com/openforcefield/openforcefield/pull/327>`_: Fix units in tip3p.offxml (note that this file is still not loadable by current toolkit)
* `PR #325 <https://github.com/openforcefield/openforcefield/pull/325>`_: Fix solvent box for provided test system to resolve periodic clashes.
* `PR #325 <https://github.com/openforcefield/openforcefield/pull/325>`_: Add informative message containing Hill formula when a molecule can't be matched in ``Topology.from_openmm``.
* `PR #325 <https://github.com/openforcefield/openforcefield/pull/325>`_: Provide warning or error message as appropriate when a molecule is missing stereochemistry.
* `PR #316 <https://github.com/openforcefield/openforcefield/pull/316>`_: Fix formatting issues in GBSA section of SMIRNOFF spec
* `PR #308 <https://github.com/openforcefield/openforcefield/pull/308>`_: Cache molecule SMILES to improve system creation speed
* `PR #306 <https://github.com/openforcefield/openforcefield/pull/306>`_: Allow single-atom molecules with all zero coordinates to be converted to OE/RDK mols
* `PR #313 <https://github.com/openforcefield/openforcefield/pull/313>`_: Fix issue where constraints are applied twice to constrained bonds

0.2.2 - Bugfix release
----------------------

This release modifies an example to show how to parameterize a solvated system, cleans up backend code, and makes several improvements to the README.

Bugfixes
""""""""
* `PR #279 <https://github.com/openforcefield/openforcefield/pull/279>`_: Cleanup of unused code/warnings in main package ``__init__``
* `PR #259 <https://github.com/openforcefield/openforcefield/pull/259>`_: Update T4 Lysozyme + toluene example to show how to set up solvated systems
* `PR #256 <https://github.com/openforcefield/openforcefield/pull/256>`_ and `PR #274 <https://github.com/openforcefield/openforcefield/pull/274>`_: Add functionality to ensure that links in READMEs resolve successfully


0.2.1 - Bugfix release
----------------------

This release features various documentation fixes, minor bugfixes, and code cleanup.

Bugfixes
""""""""
* `PR #267 <https://github.com/openforcefield/openforcefield/pull/267>`_: Add neglected ``<ToolkitAM1BCC>`` documentation to the SMIRNOFF 0.2 spec
* `PR #258 <https://github.com/openforcefield/openforcefield/pull/258>`_: General cleanup and removal of unused/inaccessible code.
* `PR #244 <https://github.com/openforcefield/openforcefield/pull/244>`_: Improvements and typo fixes for BRD4:inhibitor benchmark

0.2.0 - Initial RDKit support
-----------------------------

This version of the toolkit introduces many new features on the way to a 1.0.0 release.

New features
""""""""""""

* Major overhaul, resulting in the creation of the `SMIRNOFF 0.2 specification <https://open-forcefield-toolkit.readthedocs.io/en/master/smirnoff.html>`_ and its XML representation
* Updated API and infrastructure for reference SMIRNOFF :class:`ForceField` implementation
* Implementation of modular :class:`ParameterHandler` classes which process the topology to add all necessary forces to the system.
* Implementation of modular :class:`ParameterIOHandler` classes for reading/writing different serialized SMIRNOFF forcefield representations
* Introduction of :class:`Molecule` and :class:`Topology` classes for representing molecules and biomolecular systems
* New :class:`ToolkitWrapper` interface to RDKit, OpenEye, and AmberTools toolkits, managed by :class:`ToolkitRegistry`
* API improvements to more closely follow `PEP8 <https://www.python.org/dev/peps/pep-0008/>`_ guidelines
* Improved documentation and examples

0.1.0
-----

This is an early preview release of the toolkit that matches the functionality described in the preprint describing the SMIRNOFF v0.1 force field format: `[DOI] <https://doi.org/10.1101/286542>`_.

New features
""""""""""""

This release features additional documentation, code comments, and support for automated testing.

Bugfixes
""""""""

Treatment of improper torsions
''''''''''''''''''''''''''''''

A significant (though currently unused) problem in handling of improper torsions was corrected.
Previously, non-planar impropers did not behave correctly, as six-fold impropers have two potential chiralities.
To remedy this, SMIRNOFF impropers are now implemented as three-fold impropers with consistent chirality.
However, current force fields in the SMIRNOFF format had no non-planar impropers, so this change is mainly aimed at future work.