# Charmm36 parameter preparation for a small molecule

**URL:** <https://gromacs.bioexcel.eu/t/charmm36-parameter-preparation-for-a-small-molecule/1098>\
**Category:** User discussions\
**Created:** [November 17, 2020, 5:25am UTC](https://gromacs.bioexcel.eu/t/charmm36-parameter-preparation-for-a-small-molecule/1098 "2020-11-17T05:25:10Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![mijiddorj](https://avatars.discourse-cdn.com/v4/letter/m/779978/32.png) [@mijiddorj](https://gromacs.bioexcel.eu/u/mijiddorj)\
**Post date:** [November 17, 2020, 5:25am UTC](https://gromacs.bioexcel.eu/t/charmm36-parameter-preparation-for-a-small-molecule/1098/1 "2020-11-17T05:25:10Z")

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Dear Gmx users,  
I want to simulate folding simulation of peptide in water-HFIP solution using gromacs.  
I would like to prepare charmm36 parameters for hexafluropropanol (HFIP) instead of using CgenFF for the parameters.  
Can I convert the parameter from Gromos96 force field to Charmm36?

Best regards,

Mijiddorj

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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:** [November 17, 2020, 6:19pm UTC](https://gromacs.bioexcel.eu/t/charmm36-parameter-preparation-for-a-small-molecule/1098/2 "2020-11-17T18:19:55Z")

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> [@mijiddorj](#):
>
> Can I convert the parameter from Gromos96 force field to Charmm36?

You can’t convert one force field to another.

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**Author:** ![Hamid](https://avatars.discourse-cdn.com/v4/letter/h/5fc32e/32.png) [@Hamid](https://gromacs.bioexcel.eu/u/Hamid)\
**Post date:** [November 17, 2020, 10:49pm UTC](https://gromacs.bioexcel.eu/t/charmm36-parameter-preparation-for-a-small-molecule/1098/3 "2020-11-17T22:49:12Z")

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> [@mijiddorj](#):
>
> Gromos96 force field

no, Gromos96 force field is united atom and charmm36 is all atom.