[gmx-users] updates about ACPYPE

Alan alanwilter at gmail.com
Sat Aug 30 12:41:29 CEST 2014

Dear community,

Many thinks for all of you who uses ACPYPE and my sincere apologises for
those who have been facing issues when running ACPYPE in “amb2gmx” module
to convert to Gromacs files with Amber Forcefields 12SB and 14SB.

I am aware of this issue for more than a year, since AmberTools13 were

The problem is simple: Amber new forcefields introduced new atom types
whose names start with a digit, and Gromacs does not accept them. The
simply solution is to prefix these atom types with any letter.

I am really sorry for not doing it straightforward a year ago. Mostly lack
of time to consider some further implications, mainly how/if Gromacs  would
handle these new FF12SB and FF14SB, which is still an open question.

So, for downloading or updating ACPYPE, please have a look at:


Install anew:
svn checkout

or simply (for those who already have ACPYPE):
svn update

Many thanks,

Alan Wilter SOUSA da SILVA, DSc
Bioinformatician, UniProt
European Bioinformatics Institute (EMBL-EBI)
European Molecular Biology Laboratory
Wellcome Trust Genome Campus
Cambridge CB10 1SD
 United Kingdom
Tel: +44 (0)1223 494588

More information about the gromacs.org_gmx-users mailing list