[gmx-users] Effect of pressure coupling frequency on gpu simulations

Trayder trayder.thomas at monash.edu
Wed May 22 06:32:32 CEST 2013

Hi all,
I've been running 5fs timestep simulations successfully without gpus
(united-atom, HEAVYH). When continuing the same simulations on a gpu cluster
utilising the verlet cutoff-scheme they crash within 20 steps. Reducing the
timestep to 2fs runs smoothly, however I noticed the message:

Making this change manually led to crashing simulations as nstcalclr,
nsttcouple and nstpcouple default to the value of nstlist. After defining
them all separately I was able to determine that the simulation exploding
was dependent entirely on nstpcouple and by lowering it to 5 (from the
default 10) I was able to run simulations at a 5fs timestep.

So, my questions: Is lowering nstpcouple a legitimate solution or just a
The simulation runs with nstcalclr and nsttcouple set to 50 along with
nstlist. Is nstlist the only setting that should be increased when utilising

Thanks in advance,

P.S. The working mdp file:

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