# Save trajectory frame based on rmsd value

**URL:** <https://gromacs.bioexcel.eu/t/save-trajectory-frame-based-on-rmsd-value/5857>\
**Category:** User discussions\
**Created:** [February 23, 2023, 10:52am UTC](https://gromacs.bioexcel.eu/t/save-trajectory-frame-based-on-rmsd-value/5857 "2023-02-23T10:52:31Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Harry](https://avatars.discourse-cdn.com/v4/letter/h/f6c823/32.png) [@Harry](https://gromacs.bioexcel.eu/u/Harry)\
**Post date:** [February 23, 2023, 10:52am UTC](https://gromacs.bioexcel.eu/t/save-trajectory-frame-based-on-rmsd-value/5857/1 "2023-02-23T10:52:31Z")

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GROMACS version:2022  
GROMACS modification:No  
BS"D

Hi,

Is there a way to use gmx rms and if a frame has an rmsd above or below a certain value relative to the reference structure, save that frame in a new xtc file?

Thanks

Harry