gmx mdrun -v -deffnm em

Back Off! I just backed up em.log to ./em.log.

Running on 1 node with total 8 cores, 16 logical cores

Hardware detected:

CPU info:

Vendor: GenuineIntel

Brand: Intel(R) Xeon(R) CPU E5620 @ 2.40GHz

SIMD instructions most likely to fit this hardware: SSE4.1

SIMD instructions selected at GROMACS compile time: SSE4.1

Reading file em.tpr, VERSION 5.1.5 (single precision)

Using 16 MPI threads

Using 1 OpenMP thread per tMPI thread

Back Off! I just backed up em.trr to ./em.trr.

Back Off! I just backed up em.edr to ./em.edr.

Steepest Descents:

Tolerance (Fmax) = 1.00000e+03

Number of steps = 100000

Step= 0, Dmax= 1.0e-02 nm, Epot= 9.29257e+19 Fmax= inf, atom= 8167

Step= 14, Dmax= 1.2e-06 nm, Epot= 9.29257e+19 Fmax= inf, atom= 8167

Energy minimization has stopped, but the forces have not converged to the

requested precision Fmax < 1000 (which may not be possible for your system).

It stopped because the algorithm tried to make a new step whose size was too

small, or there was no change in the energy since last step. Either way, we

regard the minimization as converged to within the available machine

precision, given your starting configuration and EM parameters.

Double precision normally gives you higher accuracy, but this is often not

needed for preparing to run molecular dynamics.

You might need to increase your constraint accuracy, or turn

off constraints altogether (set constraints = none in mdp file)

writing lowest energy coordinates.

Back Off! I just backed up em.gro to ./#em.gro.3#

Steepest Descents converged to machine precision in 15 steps,

but did not reach the requested Fmax < 1000.

Potential Energy = 9.2925744e+19

Maximum force = inf on atom 8167

Norm of force = inf

NOTE: 8 % of the run time was spent in domain decomposition,

13 % of the run time was spent in pair search,

you might want to increase nstlist (this has no effect on accuracy)