[gmx-users] energy minimization
Madhuri Agashe
magashe at CLEMSON.EDU
Tue Feb 3 20:00:01 CET 2004
While doing energy minimization, what is the effect of specifying nsteps?
Does nsteps decide the number of steps for which minimization will run?
From the manual I thought that this would be decided by emtol.
But for a minimization run that I ran, I first did not specify nsteps.
This is what I saw in the log:
Steepest Descents:
Tolerance = 1.00000e+03
Number of steps = 0
Stepsize too small (7.31232e-07 nm)Converged to machine precision,
but not to the requested precision (1000)
writing lowest energy coordinates.
Steepest Descents did not converge in 0 steps
Potential Energy = 6.86585e+10
Maximum force: 3.51153e+05
**********************************************************
I then ran the same minimization again this time specifying nsteps=5000
This is the output I got:
Steepest Descents:
Tolerance = 1.00000e+03
Number of steps = 5000
Stepsize too small (7.31232e-07 nm)Converged to machine precision,
but not to the requested precision (1000)
writing lowest energy coordinates.
Steepest Descents did not converge in 40 steps
Potential Energy = 6.86585e+10
Maximum force: 3.51153e+05
************************************************************************
The potential energy and the maximum force at the end of both the run seems
to be the same. Then what is the significance of 40 steps and 0 steps?
This is a little confusing!
Madhuri Agashe
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