# Contribution to pressure tensor from water

**URL:** <https://gromacs.bioexcel.eu/t/contribution-to-pressure-tensor-from-water/5808>\
**Category:** User discussions\
**Created:** [February 15, 2023, 5:21pm UTC](https://gromacs.bioexcel.eu/t/contribution-to-pressure-tensor-from-water/5808 "2023-02-15T17:21:21Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![roshanshrestha](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/roshanshrestha/32/515_2.png) [@roshanshrestha](https://gromacs.bioexcel.eu/u/roshanshrestha)\
**Post date:** [February 15, 2023, 5:21pm UTC](https://gromacs.bioexcel.eu/t/contribution-to-pressure-tensor-from-water/5808/1 "2023-02-15T17:21:21Z")

</div>

GROMACS version: 2021  
GROMACS modification: Yes  
I have an infinite CG model of the material solvated in water. I am trying to apply a uniaxial deformation along a particular x-axis; the mdp settings in gromacs are below.

```
tcoupl = v-rescale
tc-grps = SOLID W_ION
tau_t = 1.0 1.0
ref_t = 298 298
Pcoupl = parrinello-rahman
Pcoupltype = anisotropic
tau_p = 12.0  
compressibility = 0.0 3e-4 3e-4 0.0 0.0 0.0
ref_p = 0.0 1.0 1.0 0.0 0.0 0.0
deform = 0.002 0 0 0 0 0

```

Stress is computed as negative of the pressure tensor -P\_{xx}. I wonder if water will affect my results, as I believe the Pressure is computed for the whole system. Previously, I used to pull one end of the model, keeping the other side fixed. Here, I am just pulling the box. Any suggestions? Thanks.