[gmx-users] Gromos DPPC bilayer: different results for 4.0.7 and 4.6.5

[Mirco Wahab]

On 16.12.2013 21:10, Lutz Maibaum wrote:
> I am running MD simulations of DPPC bilayers with the Gromos force field, and I am seeing some differences between using Gromacs 4.0.7 and 4.5.5/4.6.5 that I do not understand. It would be great if someone had any insight into what's going on here.

Lutz, from your provided files I can read you use
twin-range cutoff RF-electrostatics for 54A7:
      rcoulomb = rvdw = 1.4 at rlist = 0.8 w/nstlist = 5

are these values intended? I remember a posting of Berk Hess
some time ago where he mentioned that the "newer" Gromacs
versions would get a better intergation scheme for this
case (I could not find the source). This might be one of
the reasons for such discrepancies?

BTW - a good check would be a simple box of  say 15,625
SPC water - at which water density would the combination
of your parameters and the actual algorithm knock in.

Regards

M.