Since 2016, I'm on an extended break from CGenFF development. While I'm still hoping for future circumstances that will allow me to take up a role in the advancement of force fields for atomistic simulations of biological systems, for now:
The CGenFF program continues being available as a web service for non-commercial use at cgenff.umaryland.edu. It is updated frequently by the MacKerell lab in collaboration with SilcsBio, LLC.
A correspondingly updated version of the requisite force field files can be downloaded from the MacKerell lab's (additive) force field page.
If you wish to use CGenFF commercially, make the CGenFF program part of a software pipeline, or simply need higher throughput than the web service can provide, binary licenses (free-of-charge for not-for-profit use) can be obtained by e-mailing email@example.com.
I will not react to e-mails about CGenFF. Questions should be directed to firstname.lastname@example.org.
I may possibly make an exception for really fundamental issues. Note that structures that make no chemical sense, files that are formatted incorrectly, hard-to-understand error messages,... are the opposite of fundamental (and are in fact covered by the FAQ).
The following are archived CGenFF-related pages that are kept here mostly for posterity. They largely reflect my research activities at the University of Maryland, Baltimore up to the end of 2015.
CGenFF tutorials; some of it may be obsoleted by FFParam.
CGenFF Frequently Asked Questions: FAQ about general force field development and specifically the CGenFF Force Field, as opposed to the FAQ about the CGenFF program.
Usage information for the CGenFF program for automatic atom typing and assignment of parameters and charges by analogy.