This Python module is designed to be run with OpenMM in order to simulate grand canonical Monte Carlo (GCMC) insertion and deletion moves of water molecules. This allows the particle number to vary according to a fixed chemical potential, and offers enhanced sampling of water molecules in occluded binding sites. The theory behind our work on GCMC sampling can be found in the References section below.

This module can be installed from this directory by running the following command:

python setup.py install

The unit tests can then be carried out by running the following command from this directory:

python setup.py test

The dependencies of this module can be installed as:

conda install -c conda-forge -c omnia openmmtools
pip install lxml

Many of grand's dependencies (openmm, mdtraj, pymbar, parmed) are also dependencies of openmmtools, and will be installed alongside openmmtools.

Alternatively, grand and its dependencies can be installed via conda:

conda install -c omnia -c anaconda -c conda-forge -c essexlab grand

Several (very short) examples of how this module is ran alongside OpenMM can be found in the examples/ directory. Additional examples and documentation are also available, although please note that the examples listed within the grand-paper repo are intended to be run using version 1.0.x of grand and may not work with later versions.

The grand module is released under the MIT licence. If results from this module contribute to a publication, we only ask that you cite Ref. 1, below. A publication describing the implementation of grand canonical nonequilibrium candidate Monte Carlo (GCNCMC) is currently being prepared for submission - the citation details will be made available when possible. Additional references describing the theory upon which the GCMC implemention in grand are also provided below (Refs. 2-3).

• Marley Samways <[email protected]>
• Hannah Bruce Macdonald
• Ollie Melling <[email protected]>
• Will Poole <[email protected]>

If you have any problems or questions regarding this module, please contact one of the contributors, or send an email to <[email protected]>.

1. M. L. Samways, H. E. Bruce Macdonald, J. W. Essex, J. Chem. Inf. Model., 2020, 60, 4436-4441, DOI: https://doi.org/10.1021/acs.jcim.0c00648
2. G. A. Ross, M. S. Bodnarchuk, J. W. Essex, J. Am. Chem. Soc., 2015, 137, 47, 14930-14943, DOI: https://doi.org/10.1021/jacs.5b07940
3. G. A. Ross, H. E. Bruce Macdonald, C. Cave-Ayland, A. I. Cabedo Martinez, J. W. Essex, J. Chem. Theory Comput., 2017, 13, 12, 6373-6381, DOI: https://doi.org/10.1021/acs.jctc.7b00738