# Continuing umbrella sampling simulation

**URL:** <https://gromacs.bioexcel.eu/t/continuing-umbrella-sampling-simulation/2386>\
**Category:** User discussions\
**Created:** [June 20, 2021, 4:24pm UTC](https://gromacs.bioexcel.eu/t/continuing-umbrella-sampling-simulation/2386 "2021-06-20T16:24:23Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![mjm91](https://avatars.discourse-cdn.com/v4/letter/m/54ee81/32.png) [@mjm91](https://gromacs.bioexcel.eu/u/mjm91)\
**Post date:** [June 20, 2021, 4:24pm UTC](https://gromacs.bioexcel.eu/t/continuing-umbrella-sampling-simulation/2386/1 "2021-06-20T16:24:23Z")

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GROMACS version:2018  
GROMACS modification: No

Hi guys, I have been trying to continue some umbrella sampling simulations. Due to computational time, some of my simulations are aborted. I am trying to continue the simulation from the checkpoint file using the command: (all my files are named as nvt.xtc, nvt.tpr etc.)

gmx mdrun -v -cpi nvt.cpt -deffnm nvt

but I am receiving an error: saying “2 of the 5 output files are absent nvt\_pullf.xvg and nvt\_pullx.xvg, or modified or named differently”

However, this is not the case, both of these two files are present in the working directory and have not been renamed or modified.

I am a bit confused as I know that this is the standard way to continue or restart a simulation from cpt files, please let me know if anything else is required to be done

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**Author:** ![Ali](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/ali/32/170_2.png) [@Ali](https://gromacs.bioexcel.eu/u/Ali)\
**Post date:** [July 8, 2021, 2:37pm UTC](https://gromacs.bioexcel.eu/t/continuing-umbrella-sampling-simulation/2386/2 "2021-07-08T14:37:19Z")

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You can either explicitly name all the output files (.xtc, .trr, .xvg, .edr, etc.) instead of using `-deffnm` or else, you can use the `-noappend` option. The problem would be that you’ll get discontinuous trajectories, which should be analysed together later on.

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**Author:** ![mjm91](https://avatars.discourse-cdn.com/v4/letter/m/54ee81/32.png) [@mjm91](https://gromacs.bioexcel.eu/u/mjm91)\
**Post date:** [July 9, 2021, 7:00am UTC](https://gromacs.bioexcel.eu/t/continuing-umbrella-sampling-simulation/2386/3 "2021-07-09T07:00:52Z")

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Thank you Ali for the suggestion, I think both options you have mentioned are very much viable, thanks