[gmx-users] problem with the max number of atom in charge group

Nicolas Sapay nsapay at ucalgary.ca
Thu Jun 14 02:25:42 CEST 2007

Hello everybody,

I'm trying to use a DPPC bilayers with charges from the Jacob Sonne et 
al. study (Biophys J., 2007). The problem is that the authors have 
defined a single group for the whole DPPC molecule. This allow them to 
define new accurate charge for the head group atoms and the first atoms 
of the acyl chains. It is a problem with Gromacs which tolerate only 32 
atoms per group (When I try to minimize my system, I've got the error : 
Max #atoms in a charge group...). In Gromacs, is it possible to defined 
groups with a net charge different form an integer, like 0.026042? Would 
it be a problem if I use PME? Note that the net charge of the molecule 
is still zero, of course.



[ Nicolas SAPAY, Ph.D. ]
University of Calgary, Dept. of Biological Sciences
2500 University drive NW, Calgary AB, T2N 1N4, Canada
Tel: (403) 220-6869
Fax: (403) 289-9311

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