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<DIV><FONT size=2 face=Arial>Hi, all,</FONT></DIV>
<DIV><FONT size=2 face=Arial> I was wondering about the force
given by Gromacs. One is in the .trr and .tpr file. When I read then with
gmxdump, they are all zeros:</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>traj.trr frame 0:<BR>
natoms= 24000
step= 0
time=0.0000000e+00 lambda=
0<BR> box (3x3):<BR>
box[ 0]={ 3.24900e+00, 0.00000e+00,
0.00000e+00}<BR> box[ 1]={
0.00000e+00, 5.62743e+00,
0.00000e+00}<BR> box[ 2]={
0.00000e+00, 0.00000e+00, 1.04120e+01}</FONT></DIV>
<DIV><FONT size=2 face=Arial> f
(24000x3):<BR> f[ 0]={
0.00000e+00, 0.00000e+00,
0.00000e+00}<BR> f[ 1]={
0.00000e+00, 0.00000e+00,
0.00000e+00}<BR> f[ 2]={
0.00000e+00, 0.00000e+00,
0.00000e+00}<BR> f[ 3]={
0.00000e+00, 0.00000e+00, 0.00000e+00}</FONT></DIV>
<DIV><FONT size=2 face=Arial>....</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>When I use mdrun -pforce 0 to get all the non-zero
force, I get:</FONT></DIV>
<DIV><FONT size=2 face=Arial>step 0 atom 4687
x 0.975 3.189 0.781
force 3.58158e+02<BR>step 0 atom 4688
x 0.975 3.189 0.586
force 7.16316e+00<BR>step 0 atom 4689
x 0.975 3.189 0.586
force 3.65324e+02<BR>step 0 atom 4690
x 0.812 3.095 1.041
force 3.58167e+02<BR>step 0 atom 4691
x 0.812 3.095 0.846
force 7.16314e+00<BR>....</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Why this happens? Thanks in advance.</FONT></DIV>
<DIV><FONT size=2 face=Arial>Shuangxing Dai</FONT></DIV></BODY></HTML>