# How to get the TIP4P/2005 parameter files?

**URL:** <https://gromacs.bioexcel.eu/t/how-to-get-the-tip4p-2005-parameter-files/4126>\
**Category:** User discussions\
**Created:** [May 7, 2022, 7:02am UTC](https://gromacs.bioexcel.eu/t/how-to-get-the-tip4p-2005-parameter-files/4126 "2022-05-07T07:02:14Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![subhasreeghosh4](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/subhasreeghosh4/32/1479_2.png) [@subhasreeghosh4](https://gromacs.bioexcel.eu/u/subhasreeghosh4)\
**Post date:** [May 7, 2022, 7:02am UTC](https://gromacs.bioexcel.eu/t/how-to-get-the-tip4p-2005-parameter-files/4126/1 "2022-05-07T07:02:14Z")

</div>

GROMACS version:2021.1  
GROMACS modification: no  
Hi all,  
I am Subhasree, want to start MD simulation on protein cold denaturation. From previous studies I got to know that people are using TIP4P/2005 water model for very cold temperature as it’s optimised for that. As it’s not inbuilt in Charmm36-jul2021 so I need the .itp file and .gro file for using this water model. But I am unable to find the .gro file. I got the .itp file from one website. Please help me to get the .gro file. And give me suggestions regarding this issue.  
Thanks and regards,  
Subharee

---

<div class="post-metadata">

**Author:** ![sodiumnitrate](https://avatars.discourse-cdn.com/v4/letter/s/eada6e/32.png) [@sodiumnitrate](https://gromacs.bioexcel.eu/u/sodiumnitrate)\
**Post date:** [May 8, 2022, 10:05am UTC](https://gromacs.bioexcel.eu/t/how-to-get-the-tip4p-2005-parameter-files/4126/2 "2022-05-08T10:05:12Z")

</div>

If you look [here](http://www.sklogwiki.org/SklogWiki/index.php/TIP4P_model_of_water) and [here](http://www.sklogwiki.org/SklogWiki/index.php/TIP4P/2005_model_of_water), you can see that the only difference between TIP4P and TIP4P/2005 in terms of geometry is the location of the virtual site. You could copy the `.gro` file for TIP4P and edit it such that r\_OM (the oxygen-virtual site distance) is the correct value.

---

<div class="post-metadata">

**Author:** ![subhasreeghosh4](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/subhasreeghosh4/32/1479_2.png) [@subhasreeghosh4](https://gromacs.bioexcel.eu/u/subhasreeghosh4)\
**Post date:** [May 9, 2022, 5:24am UTC](https://gromacs.bioexcel.eu/t/how-to-get-the-tip4p-2005-parameter-files/4126/3 "2022-05-09T05:24:26Z")

</div>

thank you so much for your suggestion. I will try the same