Hi Silvia, The .xtc file does not contain velocities. You'll need to use the .trr file.
Cheers, Tsjerk On Tue, Jul 2, 2013 at 8:25 PM, Silvia <silviadilecc...@gmail.com> wrote: > Dear users and experts, > I am new in the list and I am writing because I have a problem to get > velocities from the trajectory file. When I use this command line g_traj -n > index.ndx -s topol.tpr -f traj.xtc -ov, I obtain the veloc.xvg file but > there is no data inside. I have the same problem on the force.xvg (-of) > file > but not on the coord.xvg one (-ox). So there is no information about the > velocities and the forces in the trajectory file. I enclose the output > parameters of my *.mdp file. > > ; RUN CONTROL PARAMETERS > integrator = md > ; Start time and timestep in ps > tinit = 0 > dt = 0.002 > nsteps = 2500000 > ; For exact run continuation or redoing part of a run > init_step = 0 > > ; OUTPUT CONTROL OPTIONS > ; Output frequency for coords (x), velocities (v) and forces (f) > nstxout = 1000 > nstvout = 1000 > nstfout = 1000 > ; Output frequency for energies to log file and energy file > nstlog = 1000 > nstcalcenergy = -1 > nstenergy = 1000 > ; Output frequency and precision for .xtc file > nstxtcout = 1000 > xtc-precision = 1000 > ; This selects the subset of atoms for the .xtc file. You can > ; select multiple groups. By default all atoms will be written. > xtc-grps = > ; Selection of energy groups > energygrps = > > Can someone help me to solve this problem? > Thank you in advance. > > Silvia > > > > -- > View this message in context: > http://gromacs.5086.x6.nabble.com/Cannot-get-velocities-from-the-trajectory-file-tp5009511.html > Sent from the GROMACS Users Forum mailing list archive at Nabble.com. > -- > gmx-users mailing list gmx-users@gromacs.org > http://lists.gromacs.org/mailman/listinfo/gmx-users > * Please search the archive at > http://www.gromacs.org/Support/Mailing_Lists/Search before posting! > * Please don't post (un)subscribe requests to the list. Use the > www interface or send it to gmx-users-requ...@gromacs.org. > * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists > -- Tsjerk A. Wassenaar, Ph.D. -- gmx-users mailing list gmx-users@gromacs.org http://lists.gromacs.org/mailman/listinfo/gmx-users * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/Search before posting! * Please don't post (un)subscribe requests to the list. Use the www interface or send it to gmx-users-requ...@gromacs.org. * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists