[gmx-users] velocity was not present from trjconv

[Albert]

Hello:

  I am using Gromacs4.6 and I extract one of my frame into .gro file by 
command:

trjconv_mpi -f md.xtc -s md.tpr -dump 25000 -o md.gro

I found that the velocity information was not present in this 
25ns-md.gro file:



Generated by trjconv : Protein t= 25000.00000
54178
     1TYR      N    1   1.696   3.993   8.140
     1TYR     H1    2   1.658   4.068   8.196
     1TYR     H2    3   1.719   4.031   8.050
     1TYR     H3    4   1.630   3.919   8.122
     1TYR     CA    5   1.822   3.938   8.210
     1TYR     HA    6   1.865   4.020   8.268
     1TYR     CB    7   1.790   3.814   8.300
     1TYR    HB1    8   1.883   3.770   8.336
     1TYR    HB2    9   1.764   3.732   8.233
     1TYR     CG   10   1.696   3.845   8.416
     1TYR    CD1   11   1.745   3.930   8.520
     1TYR    HD1   12   1.847   3.967   8.520
...

Does anybody knows what happen? The final md output md.gro file do 
contains velocity information:

Protein
54178
     1TYR      N    1   1.747   4.039   8.153 -0.1860  0.0829  0.0094
     1TYR     H1    2   1.694   4.084   8.226  2.0932 -0.4724  2.1614
     1TYR     H2    3   1.804   4.115   8.117 -1.6223  0.9380 -0.5483
     1TYR     H3    4   1.682   4.001   8.086  0.6678 -0.6031 -0.4474
     1TYR     CA    5   1.826   3.927   8.204 -0.5364 -0.8546 -0.6273
     1TYR     HA    6   1.892   3.958   8.285  0.3239 -2.3918 -0.7049
     1TYR     CB    7   1.732   3.813   8.243  0.4625 -0.6033 -0.2530
     1TYR    HB1    8   1.791   3.725   8.265 -1.7147 -1.9740  0.4749
     1TYR    HB2    9   1.660   3.783   8.166 -0.2485  2.0549 -0.7384
     1TYR     CG   10   1.663   3.842   8.377 -0.0029  0.0693 -0.2885
     1TYR    CD1   11   1.739   3.893   8.481 -0.5325 -0.8010 -0.1664
     1TYR    HD1   12   1.841   3.925   8.465  0.0708 -2.2306  0.7255
     1TYR    CE1   13   1.680   3.925   8.606  0.5957  0.0504 -0.4752
     1TYR    HE1   14   1.728   3.974   8.689  1.1798 -3.6443  1.5406


THX

Albert