[gmx-users] mdrun crashing on Power4/P690+

[Fiona Reid]

Dear Gromacs Users,

I have also experienced problems running Gromacs 3.2.1 on an
IBM P690+ with 1.7 GHz POWER4 processors. 

The following options were used to compile the code. 

Build 1: 

OS: AIX 5.2
Fortran Compiler: XL Fortran for AIX version 8.1.1
C compiler: C for AIX Compiler, Version 6

LDFLAGS=-L/usr/local/packages/fftw/lib
CPPFLAGS=-I/usr/local/packages/fftw/include
CC=xlc_r -q64
F77=xlf_r -q64
CFLAGS=-O3 -qarch=pwr4 -qtune=pwr4 
FFLAGS=-O3 -qarch=pwr4 -qtune=pwr4
OBJECT_MODE=64
MPICC=mpcc_r -q64

Build 2: As above but with (Following the suggestion of Campbell Millar
http://www.gromacs.org/pipermail/gmx-users/2004-June/010800.html )

-O2 and -qmaxmem=-1 

I have attempted to run both the 'demo' script from the 
tutor/gmxdemo and the water demo from tutor/water. In 
each case the demos ran successfully with Gromacs 3.1.4. 

The 'demo' script crashes at the first call of mdrun with 
the error message:

<snip>
Steepest Descents: 
   Tolerance (Fmax)   =  1.00000e+03
   Number of steps    =          100
Segmentation fault (core dumped)
mdrun finished

The water demo crashes as follows:

Reading file topol.tpr, VERSION 3.2.1 (single precision)
starting mdrun 'Pure Water'
10000 steps,     20.0 ps.

Wrote pdb files with previous and current coordinates

Back Off! I just backed up step0.pdb to ./#step0.pdb.1#
Wrote pdb files with previous and current coordinates
Warning: Only triclinic boxes with the first vector parallel to the x-axis
and the second vector in the xy-plane are supported.
         Box (3x3):
            Box[    0]={        NaNQ,         NaNQ,         NaNQ}
            Box[    1]={        NaNQ,         NaNQ,         NaNQ}
            Box[    2]={        NaNQ,         NaNQ,         NaNQ}
         Can not fix pbc.

Back Off! I just backed up step1.pdb to ./#step1.pdb.1#
Wrote pdb files with previous and current coordinates
Warning: Only triclinic boxes with the first vector parallel to the x-axis
and the second vector in the xy-plane are supported.
         Box (3x3):
            Box[    0]={        NaNQ,         NaNQ,         NaNQ}
            Box[    1]={        NaNQ,         NaNQ,         NaNQ}
            Box[    2]={        NaNQ,         NaNQ,         NaNQ}
         Can not fix pbc.

Can anyone help? 

Thanks in advance,

Fiona Reid