[gmx-users] Steepest Descents did not converge
Derrick Guang Yuh Lee
k24dgyl at morgan.ucs.mun.ca
Wed Jul 9 18:24:01 CEST 2003
dear gmx-users
right now i am running the mdrun program in gromacs on a dppc lipid
bilayer (downloaded from the tieleman's website), and i keep on getting
this error:
---------------------------------------------------------------------------
Steepest Descents:
Tolerance = 1.00000e+02
Number of steps = 1000000
Step= 0, Dmax= 1.0e-02 nm, Epot= -2.99255e+05 Fmax= 5.37264e+03, atom=3275
Step= 1, Dmax= 1.0e-02 nm, Epot= -3.02471e+05 Fmax= 2.40785e+03, atom=3024
Step= 4, Dmax= 3.0e-03 nm, Epot= -3.02866e+05 Fmax= 1.90722e+03, atom=13315
Step= 16, Dmax= 1.8e-06 nm, Epot= -3.02866e+05 Fmax= 2.63245e+03, atom=16161
Stepsize too small (8.78906e-07 nm)Converged to machine precision,
but not to the requested precision (100)
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 did not converge in 17 steps
Potential Energy = -3.02866e+05
Maximum force: 1.90722e+03
---------------------------------------------------------------------------
i've tried editing the constraints value to 'none' or changing it to
'all-bonds', and i've changed the value of emstep, but the only way i can
get the steepest decents to converge is by making the emtol value
extremely high (emtol = 100000). any help would be appreciated.
- derrick
derrick Lee
faculty of Science
Memorial University of Newfoundland
k24dgyl at mun.ca or derrickglee at hotmail.com
"a teacher is never a giver of truth - he is a guide, a pointer to the
truth that each student must find for himself. a good teacher is merely a
catalyst."
- bruce lee
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