[gmx-users] Reproducable MD runs on two PCs

[Igor Druz]

Hello,

I am running MDs on a linux PC with OpenSuse, using:

mpirun -np 4 mdrun -v -dlb auto -reprod ....

If I repeat the calculation on the same PC, I get the same result. If I
change to another PC with RedHat I get a different result. More
specifically, I am calculating a deviation from experiment, which varies by
~20 % on changing operating systems (pretty much the same hardware on both
PCs). Is there any way to avoid such variations? I guess I am missing
something in the mdp file, which is:

cpp                 =  /usr/bin/cpp -traditional
integrator               = sd
tinit                    = 0
dt                       = 0.002
nsteps                   = 1000000

nstcomm                  = 1
nstcalcenergy            = 1
nstxout                  = 5
nstvout                  = 100
nstlog                   = 100
nstenergy                = 100

nstlist                  =  5
ns_type                  = grid

pbc                      = xyz
rlist                    = 0.9

optimize_fft             = yes
coulombtype              = pme
rcoulomb                 = 0.9
epsilon-r                = 1
rvdw                     = 0.9

constraints              = all-bonds
constraint-algorithm     = Lincs

unconstrained-start      = yes
lincs-warnangle          = 30

tc_grps                  = System
tau_t                    = 0.1
ref_t                    = 300.0

Pcoupl                   = parrinello-rahman
tau_p                    = 2
compressibility         = 4.5e-05
ref_p                    = 1.0

gen_vel                  = yes
gen_temp                 = 300.0
gen_seed                 = 173529


Many thanks for your help,
Igor
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