# Do the multiple .tpr files imply different inital velocities?

**URL:** <https://gromacs.bioexcel.eu/t/do-the-multiple-tpr-files-imply-different-inital-velocities/9147>\
**Category:** User discussions\
**Created:** [May 14, 2024, 5:35am UTC](https://gromacs.bioexcel.eu/t/do-the-multiple-tpr-files-imply-different-inital-velocities/9147 "2024-05-14T05:35:00Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![aish.warya\_2024](https://avatars.discourse-cdn.com/v4/letter/a/b5ac83/32.png) [@aish.warya\_2024](https://gromacs.bioexcel.eu/u/aish.warya_2024)\
**Post date:** [May 14, 2024, 5:35am UTC](https://gromacs.bioexcel.eu/t/do-the-multiple-tpr-files-imply-different-inital-velocities/9147/1 "2024-05-14T05:35:00Z")

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Dear gmx users,  
I need to perform four MD run with different initial velocities for the trichloroethylene-water interface . I have performed NVT equilibration with gen-vel=yes, gen-seed =-1. To run the NVT equilibration, I used the following command with `grompp` :  
grompp -f nvt.mdp -c em-tce-water.gro -r em-tce-water.gro -p topol.top -o nvt-tce-water.tpr -maxwarn 1000  
After this run, i got multiple .tpr files as nvt-tce-water.tpr, #nvt-tce-water.tpr.1# , #nvt-tce-water.tpr.2# #nvt-tce-water.tpr.3#. Further I have run four different NVT equilibration with these separate .tpr files considering them as four input files with different initial velocities by giving the command:  
mdrun -deffnm nvt-tce-water1  
mdrun -deffnm nvt-tce-water2 etc.  
that is in total 4 different NVT equilibration runs completed and I obtained the respective .gro files. After that, I have run corresponding NPT equilibration MD simulation. Is this method correct? or what shall I do inorder to produce runs with different initial velocity?

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**Author:** ![MagnusL](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/magnusl/32/2380_2.png) [@MagnusL](https://gromacs.bioexcel.eu/u/MagnusL)\
**Post date:** [May 14, 2024, 8:42am UTC](https://gromacs.bioexcel.eu/t/do-the-multiple-tpr-files-imply-different-inital-velocities/9147/2 "2024-05-14T08:42:19Z")

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You already have an active thread on this ([How to generate parallel runs with different initial velocites?](https://gromacs.bioexcel.eu/t/how-to-generate-parallel-runs-with-different-initial-velocites/9071)). It is better to keep all replies there. If you get impatient, remember that everyone here are volunteers, helping you to the best of their abilities. Do not be surprised it if takes a few days between replies.

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**Author:** ![aish.warya\_2024](https://avatars.discourse-cdn.com/v4/letter/a/b5ac83/32.png) [@aish.warya\_2024](https://gromacs.bioexcel.eu/u/aish.warya_2024)\
**Post date:** [May 14, 2024, 9:30am UTC](https://gromacs.bioexcel.eu/t/do-the-multiple-tpr-files-imply-different-inital-velocities/9147/3 "2024-05-14T09:30:22Z")

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Understood, will keep replies in the existing thread. Thanks for the reminder.I respect that everyone here is volunteering their time and expertise to assist, and I will be patient in awaiting responses.  
Thank you