<P>
dea all,<BR>
I am using gromacs-3.2.1 for simulating a protein.I used the em.mdp file given there.when i tried to energy minimize the protien it gives the following error<BR>
<BR>
Stepsize too small, or no change in energy.<BR>
Converged to machine precision,<BR>
but not to the requested precision Fmax < 2000<BR>
<BR>
Double precision normally gives you higher accuracy.<BR>
You might need to increase your constraint accuracy, or turn<BR>
off constraints alltogether (set constraints = none in mdp file)<BR>
<BR>
writing lowest energy coordinates.<BR>
<BR>
Steepest Descents converged to machine precision in 53 steps,<BR>
but did not reach the requested Fmax < 2000.<BR>
Potential Energy = -3.1566375e+05<BR>
Maximum force = 2.8458027e+03 on atom 1650<BR>
Norm of force = 1.7127547e+05<BR>
<BR>
<BR>
This is the input file i gave, <BR>
**********************************************************************************<BR>
<BR>
User spoel (236)<BR>
; Wed Nov 3 17:12:44 1993<BR>
; Input file<BR>
;<BR>
cpp = /lib/cpp<BR>
define = -DFLEX_SPC<BR>
constraints = none<BR>
integrator = steep<BR>
nsteps = 1000<BR>
;<BR>
; Energy minimizing stuff<BR>
;<BR>
emtol = 2000<BR>
emstep = 0.01<BR>
<BR>
nstcomm = 1<BR>
ns_type = grid<BR>
rlist = 1<BR>
rcoulomb = 1.0<BR>
rvdw = 1.0<BR>
Tcoupl = no<BR>
Pcoupl = no<BR>
gen_vel = no<BR>
********************************************* <BR>
Is this wrong,has the protein not energy minimized sufficiently.please tell what should be done? <BR>
cheers<BR>
smith <BR>
</P>
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