[gmx-users] MD run error

Kushal Seth kushalseth at gmail.com
Wed Apr 12 01:03:01 CEST 2006

Hi all !
I am running a MD simulation and i got

"Warning: 1-4 interaction between 1 and 6 at distance 1.102 which is
larger than the 1-4 table size 1.000 nm
These are ignored for the rest of the simulation
This usually means your system is exploding,
if not, you should increase table-extension in your mdp file"

 and then EM process goes and terminates at 26 th steps saying that

"Stepsize too small, or no change in energy.
Converged to machine precision,
but not to the requested precision Fmax < 100

Double precision normally gives you higher accuracy.
You might need to increase your constraint accuracy, or turn
off constraints alltogether (set constraints = none in mdp file)

writing lowest energy coordinates.

Steepest Descents converged to machine precision in 26 steps,
but did not reach the requested Fmax < 100.
Potential Energy  = -6.0066115e+23
Maximum force     =  1.8847882e+25 on atom 2502
Norm of force     =  5.5707627e+25".

I have tried changing the sizes and pressure couplings.Thats does not help.
PLZ advice and thanks in advance.

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