<table cellspacing="0" cellpadding="0" border="0" ><tr><td valign="top" style="font: inherit;"><DIV>I did a energy minimization on a system contain one [AuCl4]- and 503 water moleculars, by using a self-define non-bond interaction (which is obtain from ab-initio calculation), my em.mdp file is as follow:</DIV>
<DIV>title = yqq<BR>cpp = /usr/bin/cpp ; the c pre-processor<BR>define = -DFLEXILBE<BR>constraints = none<BR>integrator = steep</DIV>
<DIV>energygrps = AU CL OW H</DIV>
<DIV>energygrp_table = AU OW AU H CL OW CL H<BR>dt =0.002; ps!<BR>nsteps =40000<BR>nstlist =10<BR>ns_type =grid<BR>rlist =0.9<BR>coulombtype =User<BR>rcoulomb =0.9<BR>vdwtype
=User<BR>rvdw =1.0<BR>fourierspacing =0.12<BR>fourier_nx =0<BR>fourier_ny =0<BR>fourier_nz =0<BR>pme_order =4<BR>ewald_rtol =1e-5<BR>optimize_fft =yes<BR>;<BR>; Energy minimizing
stuff<BR>;<BR>emtol =500.0<BR>emstep =0.005</DIV>
<DIV> </DIV>
<DIV>and meanwhile, I have modifide the ffG43a1.rtp, ffG43a1bon.itp, ffG43a1nb.itp files in order to include the relative parameters. Then add a table.xvg (actually the default 6-12 Lennard Jones potential form, I just renamed it so it will be read for describing the interaction of atom pairs which are not list in the energygrp_table section) and four table****.xvg contain the interaction information of AU OW, AU CL, CL OW, CL H.</DIV>
<DIV>but unfortunatly, the corresponding em.log file is follow:</DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV>Stepsize too small, or no change in energy.<BR>Converged to machine precision,<BR>but not to the requested precision Fmax < 500</DIV>
<DIV>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)</DIV>
<DIV>Steepest Descents converged to machine precision in 12 steps,<BR>but did not reach the requested Fmax < 500.<BR>Potential Energy = -3.5686449e+04<BR>Maximum force = 1.3609032e+04 on atom 1236<BR>Norm of force = 1.6019813e+03</DIV>
<DIV> M E G A - F L O P S A C C O U N T I N G</DIV>
<DIV> RF=Reaction-Field FE=Free Energy SCFE=Soft-Core/Free Energy<BR> T=Tabulated W3=SPC/TIP3p W4=TIP4p (single or pairs)<BR> NF=No Forces</DIV>
<DIV> Computing: M-Number M-Flops % Flops<BR>-----------------------------------------------------------------------<BR> VdW(T) 1.011752 54.635 16.6<BR> Coul(T) + VdW(T) 2.659114 180.820 55.0<BR> Outer nonbonded loop
0.261041 2.610 0.8<BR> NS-Pairs 4.096803 86.033 26.2<BR> Reset In Box 0.012096 0.036 0.0<BR> Shift-X 0.018168 0.109
0.0<BR> CG-CoM 0.018168 0.055 0.0<BR> Bonds 0.000048 0.003 0.0<BR> Angles 0.000072 0.012
0.0<BR> Impropers 0.000024 0.005 0.0<BR> Virial 0.018708 0.337 0.1<BR> Settle 0.012072 3.899
1.2<BR>-----------------------------------------------------------------------<BR> Total 328.553 100.0<BR>-----------------------------------------------------------------------</DIV>
<DIV><BR> R E A L C Y C L E A N D T I M E A C C O U N T I N G</DIV>
<DIV> Computing: Nodes Number G-Cycles Seconds %<BR>-----------------------------------------------------------------------<BR> Neighbor search 1 12 0.844 0.8 77.7<BR> Force 1 12 0.180 0.2 16.5<BR> Constraints 1
23 0.004 0.0 0.4<BR> Rest 1 0.059 0.1 5.4<BR>-----------------------------------------------------------------------<BR> Total 1 1.086 1.0 100.0<BR>-----------------------------------------------------------------------</DIV>
<DIV> NODE (s) Real (s) (%)<BR> Time: 1.000 1.000 100.0<BR> (Mnbf/s) (MFlops) (steps/hour)<BR>Performance: 3.671 328.553 43200.0<BR>Finished mdrun on node 0 Wed Oct 21 23:38:48 2009</DIV>
<DIV> </DIV>
<DIV>the force is very large and I have tried to adjust "emstep" and other options but seems has no influence on the result, can anyone help me on this problem, any suggestion will be very, very grateful. Thank you.</DIV>
<DIV>By the way, I have ajusted the No. of water moleculars in the simulation box but almost has no infulence on the result.</DIV></td></tr></table><br>
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