# System getting heated with integrator=sd

**URL:** <https://gromacs.bioexcel.eu/t/system-getting-heated-with-integrator-sd/2328>\
**Category:** User discussions\
**Tags:** mdp-parameters, mdrun\
**Created:** [June 9, 2021, 12:28pm UTC](https://gromacs.bioexcel.eu/t/system-getting-heated-with-integrator-sd/2328 "2021-06-09T12:28:31Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![Yogeshb](https://avatars.discourse-cdn.com/v4/letter/y/bc79bd/32.png) [@Yogeshb](https://gromacs.bioexcel.eu/u/Yogeshb)\
**Post date:** [June 9, 2021, 12:28pm UTC](https://gromacs.bioexcel.eu/t/system-getting-heated-with-integrator-sd/2328/1 "2021-06-09T12:28:31Z")

</div>

GROMACS version: 2018.4  
GROMACS modification: No  
I am trying to equilibrate Icosane (C20H42) in octanol using mdp file (mdp\_prod.mdp), I have done short NVT (mdp\_nvt.mdp) and NPT (mdp\_npt.mdp) simulations. My system is blowing up. I noticed sudden temperature increase in the system, may be due to friction, I am using integrator = sd. I am using gromos54a7 force field. I have to use this system further for free energy calculations. mdp files are created using templet given at free energy tutorial given by Justin ([Free Energy Calculations](http://www.mdtutorials.com/gmx/free_energy/))  
please help.  
mdp files:  
[mdp\_npt.mdp](https://gromacs.bioexcel.eu/uploads/short-url/nTj9HZc1gD2olbUh8LpcGplj91k.mdp) (1.8 KB)  
[mdp\_nvt.mdp](https://gromacs.bioexcel.eu/uploads/short-url/h1HYULDz1wpB7EnnBeph6f37aXK.mdp) (1.8 KB)  
[mdp\_prod.mdp](https://gromacs.bioexcel.eu/uploads/short-url/kSQIwxSFHEYVH1mxE69HRAuDYWn.mdp) (1.8 KB)

temperature plot:  
 ![image](https://europe1.discourse-cdn.com/flex017/uploads/bioexcel1/original/1X/e6fdd4c405cd964a653d6ad5c40c1ec52eb43b12.png)