[gmx-users] md.log question

[Rui Qiao]

Dear David:
	I do an energy minmization after reading your email. Basically I
start from some configuration and let the mdrun to calculate the potential
energy. Below is what I have got:

STEEPEST DESCENTS
STEEPEST DESCENTS
   Tolerance         =         1000
Step =    14, Dmax = 1.22e-06 nm, Epot = -1.80205e+05 Fmax = 4.37923e+03
Stepsize too small Converged to machine precision,
but not to the requested precision (1000)
You might need to increase your constraint accuracy

writing lowest energy coordinates.

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

Back Off! I just backed up confout.gro to #confout.gro#
Maximum force:  3.96501e+03

STEEPEST DESCENTS did not converge in 15 steps
  Potential Energy  =          nan      

	So, it appears to me that the force itself is not large, but the
potential energy is given a NaN. Even strange is that it is giving some
potential energy (-1.80205e+05) at the beginging, but it gives a NaN at
the end.

	sincerely,

	Rui

------------------------
Rui Qiao
Research Assistant
Beckman Institute, UIUC