# Is it possible to apply npt in only x and y direction?

**URL:** <https://gromacs.bioexcel.eu/t/is-it-possible-to-apply-npt-in-only-x-and-y-direction/2715>\
**Category:** User discussions\
**Tags:** mdrun\
**Created:** [August 23, 2021, 12:42pm UTC](https://gromacs.bioexcel.eu/t/is-it-possible-to-apply-npt-in-only-x-and-y-direction/2715 "2021-08-23T12:42:59Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![sikisipra](https://avatars.discourse-cdn.com/v4/letter/s/e9a140/32.png) [@sikisipra](https://gromacs.bioexcel.eu/u/sikisipra)\
**Post date:** [August 23, 2021, 12:42pm UTC](https://gromacs.bioexcel.eu/t/is-it-possible-to-apply-npt-in-only-x-and-y-direction/2715/1 "2021-08-23T12:42:59Z")

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GROMACS version:2021.2  
GROMACS modification: Yes/No  
Dear Developers and Users,  
Is it possible to apply npt in only x and y directions but not in z-direction?

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**Author:** ![sikisipra](https://avatars.discourse-cdn.com/v4/letter/s/e9a140/32.png) [@sikisipra](https://gromacs.bioexcel.eu/u/sikisipra)\
**Post date:** [August 23, 2021, 12:55pm UTC](https://gromacs.bioexcel.eu/t/is-it-possible-to-apply-npt-in-only-x-and-y-direction/2715/2 "2021-08-23T12:55:49Z")

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I was thinking if I will change the compressibility to zero, will it  
solve the purpose?

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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:** [August 23, 2021, 1:04pm UTC](https://gromacs.bioexcel.eu/t/is-it-possible-to-apply-npt-in-only-x-and-y-direction/2715/3 "2021-08-23T13:04:31Z")

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That is exactly how you accomplish what you’re trying to do.

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**Author:** ![sikisipra](https://avatars.discourse-cdn.com/v4/letter/s/e9a140/32.png) [@sikisipra](https://gromacs.bioexcel.eu/u/sikisipra)\
**Post date:** [August 23, 2021, 1:24pm UTC](https://gromacs.bioexcel.eu/t/is-it-possible-to-apply-npt-in-only-x-and-y-direction/2715/4 "2021-08-23T13:24:09Z")

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Thank you very much Prof. J. Lemkul for your response, I am already  
implementing it.

Thanks and Regards  
Sipra Mohapatra  
PhD scholar  
Dept. of Physics,IIT jodhpur

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**Author:** ![dalip](https://avatars.discourse-cdn.com/v4/letter/d/b19c9b/32.png) [@dalip](https://gromacs.bioexcel.eu/u/dalip)\
**Post date:** [August 25, 2021, 12:34pm UTC](https://gromacs.bioexcel.eu/t/is-it-possible-to-apply-npt-in-only-x-and-y-direction/2715/5 "2021-08-25T12:34:45Z")

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Yes, it is. It depends on your system. You can control it using isotropic, semi-isotropic and an-isotropic conditions.