[Openmm-betatesters] OpenMM 6.2 beta

[Peter Eastman]

A beta release of OpenMM 6.2 is now available for testing,  The main focus of this release is on performance.  It contains dozens of different optimizations throughout the code.  The CUDA and OpenCL platforms both have large, across the board speed improvements.  The CPU platform now has a just-in-time compiler for custom expressions, so most custom forces are dramatically faster.  Multi-GPU performance on the CUDA platform is significantly improved.  And so on.

In addition to the improved computation speed, there are a few other significant new features in this release:

There is a new barostat called MonteCarloMembraneBarostat that implements features specifically needed for membrane simulations.  For example, it can apply a surface tension in the plane of the membrane, and supports new types of Monte Carlo moves, such as semi-isotropic moves and volume preserving moves.

There is a new custom force called CustomManyParticleForce.  It can implement a wide range of non-pairwise nonbonded forces, where the interaction energy depends explicitly on more than two particles at a time.

There is a reader for PDBx/mmCIF files.  This is a file format that is being pushed by wwPDB as a replacement for the old PDB format.  To use the new reader, just specify the PDBxFile class in place of PDBFile.

One important change to be aware of: in this release, the precompiled binaries we provide for Linux and Mac OS X are 64 bit only.  This change was largely forced on us by the fact that NVIDIA is dropping support for 32 bit binaries on those platforms.  Using CUDA 6.5, it is impossible to compile a 32 bit version of the CUDA platform on them.  In any case, 32 bit Linux is becoming increasingly rare, and all versions of OS X for quite a while have supported 64 bit binaries.  If you compile from source, you can still build 32 bit binaries as long as you don't need CUDA (or build against an older version of CUDA).  At least for the moment, we are continuing to provide 32 bit binaries for Windows.

OpenMM 6.2 beta is available from https://simtk.org/project/xml/downloads.xml?group_id=161.  Scroll to the bottom of the section for 6.1 and click the link that says, "List all hidden releases."  That link will only appear if you're logged in to simtk.org and you're a member of the project, so if you aren't, email me your user name and I'll add you.

Thank you for your help in testing this!

Peter