# Implementaion of polarisation in itp file

**URL:** <https://gromacs.bioexcel.eu/t/implementaion-of-polarisation-in-itp-file/4456>\
**Category:** User discussions\
**Created:** [July 12, 2022, 7:32am UTC](https://gromacs.bioexcel.eu/t/implementaion-of-polarisation-in-itp-file/4456 "2022-07-12T07:32:56Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![hema](https://avatars.discourse-cdn.com/v4/letter/h/258eb7/32.png) [@hema](https://gromacs.bioexcel.eu/u/hema)\
**Post date:** [July 12, 2022, 7:32am UTC](https://gromacs.bioexcel.eu/t/implementaion-of-polarisation-in-itp-file/4456/1 "2022-07-12T07:32:56Z")

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Dear Gromacs Users,  
I am doing simulations using Gromacs 20201.4 software. I want to add polarisation in itp file. According to the gromacs manual, the format of polarisation in itp file is:  
**[polarization]**  
**; Atom i j type alpha**  
**1 2 1 0.001**  
But I am confused about what is meant by an atom, i, j and how the parameters are taken for these. Can anyone please help me with this?  
Thank you very much in advance for your kind help.

Regards  
Hema Teherpuria