# Start simulation from xtc file?

**URL:** <https://gromacs.bioexcel.eu/t/start-simulation-from-xtc-file/6007>\
**Category:** User discussions\
**Tags:** mdrun\
**Created:** [March 20, 2023, 12:49pm UTC](https://gromacs.bioexcel.eu/t/start-simulation-from-xtc-file/6007 "2023-03-20T12:49:51Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Erik](https://avatars.discourse-cdn.com/v4/letter/e/b5ac83/32.png) [@Erik](https://gromacs.bioexcel.eu/u/Erik)\
**Post date:** [March 20, 2023, 12:49pm UTC](https://gromacs.bioexcel.eu/t/start-simulation-from-xtc-file/6007/1 "2023-03-20T12:49:52Z")

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GROMACS version: 2022.3  
GROMACS modification: No

I accidentally deleted all my files from some of my simulations that I would like to continue, but I have the .xtc files backed up on another machine. Is there any way to start a simulation from the last configuration in an xtc file and the starting .gro file? Since they’re lower precision, I assume I somehow have to extract the last configuration and do energy minimization again to get a new starting configuration?

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**Author:** ![jalemkul](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/jalemkul/32/18_2.png) [@jalemkul](https://gromacs.bioexcel.eu/u/jalemkul)\
**Post date:** [March 20, 2023, 1:05pm UTC](https://gromacs.bioexcel.eu/t/start-simulation-from-xtc-file/6007/2 "2023-03-20T13:05:30Z")

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If you perform energy minimization, you aren’t continuing the simulation because now you have an entirely new configuration. Also note that `.xtc` files do not contain velocities, so you cannot perform an exact continuation from this state. You need a corresponding `.cpt` file or the same frame as a `.trr` (assuming you saved velocities) to have any real chance of continuing. Otherwise, you’re just stating a new simulation because you have to randomize velocities again.