[gmx-users] Differing data estimates between Gromacs versions - why?

[Jernej Zidar]

Hi,
  Recently I observed that grompp gives a different data estimate if I
use either version 4.5.5 or 4.6. The difference in my case is roughly
100-fold for a small (18.000 atoms) system and all things being equal
(same gro, top, index, and mdp file):
Gromacs-4.5.5: 51428 MB
Gromacs-4.6: 600 MB

  I get the same estimate (huge) estimate whether I use the the
binaries I compiled myself (w/o openMPI) or the ones present in the
Ubuntu (12.04) repository.

  What could account for this difference?

Thanks in advance,
Jernej Zidar