[gmx-users] problems with non pbc simulations in parallel

[Berk Hess]

Hi,

This is a silly bug with nose-hoover and pbc=no.
I fixed it for 4.0.8 (if we will ever release that).

To fix it you only need to move a brace up 4 lines in src/mdlib/init.c
Or you can use the v-rescale thermostat.

Berk

--- a/src/mdlib/init.c
+++ b/src/mdlib/init.c
@@ -119,9 +119,9 @@ static void set_state_entries(t_state *state,t_inputrec *ir,
int nnodes)
     if (ir->epc != epcNO) {
       state->flags |= (1<<estPRES_PREV);
     }
-    if (ir->etc == etcNOSEHOOVER) {
-      state->flags |= (1<<estNH_XI);
-    }
+  }
+  if (ir->etc == etcNOSEHOOVER) {
+    state->flags |= (1<<estNH_XI);
   }
   if (ir->etc == etcNOSEHOOVER || ir->etc == etcVRESCALE) {
     state->flags |= (1<<estTC_INT);


> Date: Wed, 10 Mar 2010 14:16:38 +0000
> From: gmelaugh01 at qub.ac.uk
> To: gmx-users at gromacs.org
> Subject: [gmx-users] problems with non pbc simulations in parallel
> 
> Hi all
> 
> I have installed gromacs-4.0.7-parallel with open mpi. I have
> successfully ran a few short simulations on 2,3 and 4 nodes using pbc. I
> am now interested in simulating a cluster of 32 molecules with no pbc in
> parallel and the simulation doe not proceed. I have set by box vectors
> to 0 0 0 in the conf.gro file, pbc = no in the mdp file, and use
> dparticle decomposition. The feedback I get from the following command
> 
> nohup mpirun -np 2 /local1/gromacs-4.0.7-parallel/bin/mdrun -pd -s &
> 
> is
> 
> Back Off! I just backed up md.log to ./#md.log.1#
> Reading file topol.tpr, VERSION 4.0.7 (single precision)
> starting mdrun 'test of 32 hexylcage molecules'
> 1000 steps,      0.0 ps.
> [emerald:22662] *** Process received signal ***
> [emerald:22662] Signal: Segmentation fault (11)
> [emerald:22662] Signal code: Address not mapped (1)
> [emerald:22662] Failing at address: (nil)
> [emerald:22662] [ 0] /lib64/libpthread.so.0 [0x7fbc17eefa90]
> [emerald:22662] [ 1]
> /local1/gromacs-4.0.7-parallel/bin/mdrun(nosehoover_tcoupl+0x74) [0x436874]
> [emerald:22662] [ 2]
> /local1/gromacs-4.0.7-parallel/bin/mdrun(update+0x171) [0x4b2311]
> [emerald:22662] [ 3]
> /local1/gromacs-4.0.7-parallel/bin/mdrun(do_md+0x2608) [0x42dd38]
> [emerald:22662] [ 4]
> /local1/gromacs-4.0.7-parallel/bin/mdrun(mdrunner+0xe33) [0x430973]
> [emerald:22662] [ 5]
> /local1/gromacs-4.0.7-parallel/bin/mdrun(main+0x5b8) [0x431128]
> [emerald:22662] [ 6] /lib64/libc.so.6(__libc_start_main+0xe6)
> [0x7fbc17ba6586]
> [emerald:22662] [ 7] /local1/gromacs-4.0.7-parallel/bin/mdrun [0x41e1e9]
> [emerald:22662] *** End of error message ***
> --------------------------------------------------------------------------
> mpirun noticed that process rank 1 with PID 22662 on node emerald exited
> on signal 11 (Segmentation fault).
> 
> p.s I have ran several of these non pbc simulations with the same system
> in serial and have never experienced a problem. Has anyone ever come
> across this sort of problem before? and if so could you please provide
> some advice.
> 
> Many Thanks
> 
> Gavin
> 
> -- 
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