<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Thanks to all of you for offering to help with OpenMM beta testing! A beta of OpenMM 4.1 is now available for download. If you'd like to try it out, or are willing to help test it, that would be great. Feedback, suggestions, bug reports, and success reports are all helpful. Be sure to specify what OS and GPU you are using, and whether you're using the prebuilt binaries or building from source. Answers to any or all of the following questions are especially useful:<div><br></div><div>* Can you install the prebuilt binaries?</div><div>* Does the testInstallation.py script run successfully?</div><div>* Can you build from source?</div><div>* Do your existing programs/scripts/simulations work with the new version?</div><div>* Do the new features work for you?<div><br></div><div>This release contains lots of new features, bug fixes, and optimizations. Here are some of the major new features in the core library:<div><br></div><div>* CustomIntegrator</div><div>* Virtual sites</div><div>* Force groups (useful for implementing multiple time step integrators)</div><div><br></div><div>In addition, the Python API includes the following new features:</div><div><br></div><div>* Basic model editing (such as adding hydrogens and adding solvent)</div><div>* TIP4P-Ew and TIP5P water models</div><div>* StateDataReporter</div><div>* Most of the GB models supported by AMBER</div><div>* Improved documentation</div><div>* Python 3.x support</div><div><br></div><div>To download it, go to the OpenMM download page (<a href="https://simtk.org/project/xml/downloads.xml?group_id=161">https://simtk.org/project/xml/downloads.xml?group_id=161</a>). Scroll down to the bottom of the section for OpenMM 4.0 and click the link that says, "List all hidden releases". This link will only appear if you are logged in to <a href="http://simtk.org">simtk.org</a>, and you are a member of the OpenMM project. If you are not currently a project member, email me your <a href="http://simtk.org">simtk.org</a> username and I'll add you.</div><div><br></div><div>Important Note: This release does <i>not</i> support AMD GPUs under OS X. We found serious bugs in the OpenCL implementation that we haven't been able to work around, and decided the safest approach was to disable support. If you try to use the OpenCL platform on a Mac with an AMD GPU, you will get an error that no supported device is available.</div><div><br></div><div>Peter</div></div></div></body></html>