[gmx-users] something wrong with BlueGene/P

Bao Kai paeanball at gmail.com
Wed Sep 26 13:51:26 CEST 2012


Hi, all,

I did many simulations with Gromacs on CO2 Water mixtures on my
workstation with 8 cores in parallel, the results are pretty good.

For bigger simulations, I turned to the BlueGene machine. The problem
is that with exactly the same configuration files and same number of
MPI tasks( 8 here) , I always got the following problems.

   1773
   1774 step 6870: Water molecule starting at atom 1375 can not be settled.
   1775 Check for bad contacts and/or reduce the timestep if appropriate.
   1776 Wrote pdb files with previous and current coordinates
   1777
   1778 Step 6871, time 6.871 (ps)  LINCS WARNING
   1779 relative constraint deviation after LINCS:
   1780 rms 0.139809, max 0.559153 (between atoms 10 and 11)
   1781 bonds that rotated more than 30 degrees:
   1782  atom 1 atom 2  angle  previous, current, constraint length
   1783      10     11   78.5    0.1210   0.1813      0.1163
   1784      10     12   90.0    0.1523   0.1152      0.1163
   1785
   1786 step 6871: Water molecule starting at atom 4576 can not be settled.
   1787 Check for bad contacts and/or reduce the timestep if appropriate.
   1788
   1789 step 6871: Water molecule starting at atom 5794 can not be settled.
   1790 Check for bad contacts and/or reduce the timestep if appropriate.
   1791 Wrote pdb files with previous and current coordinates
   1792 Wrote pdb files with previous and current coordinates
   1793
   1794 -------------------------------------------------------
   1795 Program mdrun_bgp_d, VERSION 4.5.5
   1796 Source code file: pme.c, line: 538
   1797
   1798 Fatal error:
   1799 3 particles communicated to PME node 1 are more than 2/3 times
the cut-off out of the domain decomposition cell of their charge group
in dimension y.
   1800 This usually means that your system is not well equilibrated.
   1801 For more information and tips for troubleshooting, please
check the GROMACS
   1802 website at http://www.gromacs.org/Documentation/Errors

When I do the energy minimization or the NVT equilibration, Gromacs
worked pretty well.

The problem happened when I turned to the NPT equilibration. The
pressure and temperature were set to be 100bar and 318K respectively.
When during the NPT equlibration, the temperature and pressure keep
increasing before the program halt.

   1161
   1162 DD  step 6499 load imb.: force  6.9%
   1163
   1164            Step           Time         Lambda
   1165            6500        6.50000        0.00000
   1166
   1167    Energies (kJ/mol)
   1168           Angle        LJ (SR)  Disper. corr.   Coulomb (SR)
Coul. recip.
   1169     4.50025e+01    2.21540e+04   -7.02187e+02   -1.23033e+05
-1.27743e+04
   1170       Potential    Kinetic En.   Total Energy    Temperature
Pres. DC (bar)
   1171    -1.14310e+05    1.50736e+04   -9.92368e+04    3.74677e+02
-3.36430e+02
   1172  Pressure (bar)   Constr. rmsd
   1173     1.53825e+03    1.53151e-06
   1174
   1175 DD  step 6599 load imb.: force  5.1%
   1176
   1177            Step           Time         Lambda
   1178            6600        6.60000        0.00000
   1179
   1180    Energies (kJ/mol)
   1181           Angle        LJ (SR)  Disper. corr.   Coulomb (SR)
Coul. recip.
   1182     5.41207e+01    2.32123e+04   -7.01221e+02   -1.23852e+05
-1.27349e+04
   1183       Potential    Kinetic En.   Total Energy    Temperature
Pres. DC (bar)
   1184    -1.14022e+05    1.50532e+04   -9.89688e+04    3.82147e+02
-3.35505e+02
   1185  Pressure (bar)   Constr. rmsd
   1186     2.37940e+03    1.40409e-06
   1187
   1188 DD  step 6699 load imb.: force  4.8%
   1189
   1190            Step           Time         Lambda
   1191            6700        6.70000        0.00000
   1192
   1193    Energies (kJ/mol)
   1194           Angle        LJ (SR)  Disper. corr.   Coulomb (SR)
Coul. recip.
   1195     4.70219e+01    2.37867e+04   -6.99910e+02   -1.24021e+05
-1.26862e+04
   1196       Potential    Kinetic En.   Total Energy    Temperature
Pres. DC (bar)
   1197    -1.13574e+05    1.54884e+04   -9.80852e+04    4.03537e+02
-3.34252e+02
   1198  Pressure (bar)   Constr. rmsd
   1199     3.01172e+03    1.56366e-06
   1200
   1201 DD  step 6799 load imb.: force  6.7%
   1202
   1203            Step           Time         Lambda
   1204            6800        6.80000        0.00000
   1205
   1206    Energies (kJ/mol)
   1207           Angle        LJ (SR)  Disper. corr.   Coulomb (SR)
Coul. recip.
   1208     3.79031e+01    2.70730e+04   -6.97586e+02   -1.24088e+05
-1.24549e+04
   1209       Potential    Kinetic En.   Total Energy    Temperature
Pres. DC (bar)
   1210    -1.10129e+05    3.49837e+04   -7.51454e+04    1.00845e+03
-3.32036e+02
   1211  Pressure (bar)   Constr. rmsd
   1212     9.09741e+03    3.89773e-06

The input file for the NPT equilibration is as follows.

define = -DPOSRES ; position restrain the protein
; Run parameters
integrator = md ; leap-frog integrator
; integrator = md-vv ; leap-frog integrator
nsteps = 100000 ; 2 * 50000 = 100 ps
dt = 0.002 ; 2 fs
; Output control
nstxout = 100 ; save coordinates every 0.2 ps
nstvout = 100 ; save velocities every 0.2 ps
; ; no nstxtcout
nstenergy = 100 ; save energies every 0.2 ps
nstlog = 100 ; update log file every 0.2 ps
; Bond parameters
continuation = yes ; <---  Restarting after NVT
constraint_algorithm = lincs ; holonomic constraints
constraints = all-bonds ; all bonds (even heavy atom-H bonds) constrained
lincs_iter = 1 ; accuracy of LINCS
lincs_order = 4 ; also related to accuracy
; Neighborsearching
ns_type = grid ; search neighboring grid cells
nstlist = 5 ; 10 fs
rlist = 0.9 ; short-range neighborlist cutoff (in nm)
rcoulomb = 0.9 ; short-range electrostatic cutoff (in nm)
; rcoulomb = 1.5 ; short-range electrostatic cutoff (in nm)
rvdw = 0.9 ; short-range van der Waals cutoff (in nm)
; Electrostatics
coulombtype = PME ; Particle Mesh Ewald for long-range electrostatics
pme_order = 4 ; cubic interpolation
fourierspacing = 0.16 ; grid spacing for FFT
; Temperature coupling is on
tcoupl = V-rescale ; modified Berendsen thermostat
; tcoupl = nose-hoover ; modified Berendsen thermostat
; tc-grps = CO2 SOL ; two coupling groups - more accurate
tc-grps = System ; two coupling groups - more accurate
tau_t = 0.1 ; time constant, in ps
ref_t = 318 ; reference temperature, one for each group, in K
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; turning on pressure coupling
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; <-- Pressure coupling is on
pcoupl = Parrinello-Rahman ; Pressure coupling on in NPT
pcoupltype = isotropic ; uniform scaling of box vectors
tau_p = 2.0 ; time constant, in ps
ref_p = 100.0 ; reference pressure, in bar
compressibility = 4.5e-5 ; isothermal compressibility of water, bar^-1
; Periodic boundary conditions
pbc = xyz ; 3-D PBC
; Dispersion correction
DispCorr = EnerPres ; account for cut-off vdW scheme
; Velocity generation
gen_vel = no ; <-- Velocity generation is off
;
;

I do not know what to do. This is really kind of the worst things can
happen. I can not understand why it work on the workstation while can
not work on the BlueGene machine.

The thing is a little urgent now. If I could not go over the problem,
my project will be dead.

Any suggestions will be much appreciated.

Thank you very much.

Best Regards,
Kai



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