# Direction of pulling using direction-periodic
**URL:** https://gromacs.bioexcel.eu/t/direction-of-pulling-using-direction-periodic/153
**Category:** User discussions
**Created:** [May 18, 2020, 1:22pm UTC](https://gromacs.bioexcel.eu/t/direction-of-pulling-using-direction-periodic/153 "2020-05-18T13:22:50Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@mfernandezpendas](https://gromacs.bioexcel.eu/u/mfernandezpendas)
#### Post date: [May 18, 2020, 1:22pm UTC](https://gromacs.bioexcel.eu/t/direction-of-pulling-using-direction-periodic/153/1 "2020-05-18T13:22:50Z")
GROMACS version: 2019.5
GROMACS modification: Yes
Dear All,
I am trying to arrange a pulling simulation of a protein using an umbrella potential and direction-periodic.
I was wondering how I can impose the direction of the pulling to be along the longest diagonal of my rectangular box?
I was assuming this could be done setting pull-coord1-vec as the vector that one can find at the bottom of the gro file used by the pulling code. Is this correct? Is there any other way?
In any case, I am leaving here the pulling part of my mdp file:
indent ppull = yes
pull-coord1-groups = 0 1
pull-group1-name = ProteinC
pull-coord1-type = umbrella
pull-coord1-geometry = direction-periodic
pull-coord1-vec = 39.70966 5.95645 5.95645
pull-nstxout = 1000
pull-nstfout = 1000
pull-group1-pbcatom = 1200
pull-pbc-ref-prev-step-com = yes
Many thanks.
Best regards,
Mario
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### Author:  [@mfernandezpendas](https://gromacs.bioexcel.eu/u/mfernandezpendas)
#### Post date: [May 18, 2020, 1:24pm UTC](https://gromacs.bioexcel.eu/t/direction-of-pulling-using-direction-periodic/153/2 "2020-05-18T13:24:42Z")
Sorry, the version of GROMACS does not have any modification, that was a typo.
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### Author:  [@cblau](https://gromacs.bioexcel.eu/u/cblau)
#### Post date: [May 20, 2020, 9:36am UTC](https://gromacs.bioexcel.eu/t/direction-of-pulling-using-direction-periodic/153/3 "2020-05-20T09:36:50Z")
Hi Mairo,
his looks okay to me - as far as I know, there is no way to specify this type of pull coordinate explicitly. Note that you will have take care of the ref-coord scaling when using pressure coupling during your simulations.
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### Author:  [@mfernandezpendas](https://gromacs.bioexcel.eu/u/mfernandezpendas)
#### Post date: [May 20, 2020, 7:20pm UTC](https://gromacs.bioexcel.eu/t/direction-of-pulling-using-direction-periodic/153/4 "2020-05-20T19:20:36Z")
Many thanks!