Dear Amber users:
I got a problem when I did an energy minimization using sander with
igb=2. after 200 steps, 1-4 EEL energy is too big (see below output). I
checked the pdb file at the 200 step, it seems that hydrogen atom is too
close to nearby opposite charged atoms. I looked through Amber Archive.
someone have the similar problem as mine. it is probably caused by
"coulomb singularity". but I didn't find any way to fix it. Could Anyone
who know the answer please let me know?
Thanks
Xuelin
input for minimization:
&cntrl
imin = 1,
maxcyc= 200,
ncyc = 200,
ntb = 0,
igb = 2,
cut = 10
/
output until 200 step
NSTEP ENERGY RMS GMAX NAME
NUMBER
1 2.2320E+14 5.5226E+13 6.1959E+15 C212 15050
BOND = 7614.5838 ANGLE = 10295.7603 DIHED =
7006.8784
VDWAALS = ************* EEL = -17172.9293 EGB =
-5767.1696
1-4 VDW = 2826.7528 1-4 EEL = -6029.6140 RESTRAINT =
0.0000
NSTEP ENERGY RMS GMAX NAME
NUMBER
50 7.5926E+04 1.1788E+02 1.5699E+04 C311 11126
BOND = 43183.3868 ANGLE = 16384.4780 DIHED =
7211.9227
VDWAALS = 34584.4697 EEL = -16844.8052 EGB =
-6150.0674
1-4 VDW = 3575.6091 1-4 EEL = -6019.1613 RESTRAINT =
0.0000
NSTEP ENERGY RMS GMAX NAME
NUMBER
100 -8.6078E+03 6.5207E+00 4.3093E+02 C313 1532
BOND = 3016.2527 ANGLE = 8808.6151 DIHED =
6951.3959
VDWAALS = -999.9839 EEL = -16880.7853 EGB =
-6252.7447
1-4 VDW = 3056.8384 1-4 EEL = -6307.3457 RESTRAINT =
0.0000
NSTEP ENERGY RMS GMAX NAME
NUMBER
150 -2.6681E+06 3.9955E+08 6.2474E+10 H2 4038
BOND = 2362.1843 ANGLE = 7920.8575 DIHED =
6911.7297
VDWAALS = -1862.9807 EEL = -16849.7311 EGB =
-6275.6945
1-4 VDW = 2949.4612 1-4 EEL = -2663244.3069 RESTRAINT =
0.0000
NSTEP ENERGY RMS GMAX NAME
NUMBER
200 -5.7480E+07 1.8690E+11 2.9224E+13 H2 4038
BOND = 2362.1857 ANGLE = 7920.8598 DIHED =
6911.7297
VDWAALS = -1862.9802 EEL = -16849.7310 EGB =
-6275.6947
1-4 VDW = 2949.4612 1-4 EEL = ************* RESTRAINT =
0.0000
MAXIMUM NUMBER OF F EVALUATION EXCEEDED
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Received on Sun Sep 16 2007 - 06:07:22 PDT
