This repository is the simplest example of a hoomd plugin computing a force. It does nothing other than check the number of particles in the group passed to it are no larger than the total number of particles in a simulation. Currently this fails on linux, with the groups having an absurdly large number of molecules on the order of 2 billion.

This install procedure assumes you have conda or miniconda installed on your system, see the conda user guide for installation instructions.

To install and setup this module first clone this repository

$ git clone https://github.com/malramsay64/hoomd-simple-force

then to setup the conda environment run

$ conda env update

which will install all the prerequisites for compiling the plugin as well as installing hoomd. Once this is completed the environment needs to be activated

$ conda activate hoomd-plugins

followed by the installation of the plugin with the command

$ make install

A demonstration of the failure can be run with

$ make test

which will result in the following error message

**ERROR**: More particles in Group than in Simulation, group_size: 1318697904
Traceback (most recent call last):
  File "test/test_group.py", line 50, in <module>
    force = hoomd.simple_force.SimpleForce(rc)
  File "/home/malcolm/.miniconda/envs/hoomd-plugins/lib/python3.6/site-packages/hoomd/simple_force/force.py", line 47, in __init__
    hoomd.context.current.system_definition, group.cpp_group
RuntimeError: Error initializing SimpleForce