The CHARMM36 force field has been updated as of February 2026 and the GROMACS-formatted ports are now available: MacKerell Lab
For details on updates, please see the toppar.history file at GitHub - Lemkul-Lab/toppar_c36_releases · GitHub
There are four versions available, to account for two different versions of CGenFF as we transition to version 5.0; we are providing version 4.6 for compatibility with last year’s SilcsBio release and the topologies generated by the CGenFF server. Both entities will soon support CGenFF 5.0, so the force field is now publicly available with this release. We recommend the use of LJ-PME for treatment of van der Waals forces but we also provide the topologies and parameters for the conventional force-switching vdW approach. Happy simulating!