# Chloroform as a solvent in Charmm36 force field **URL:** \ **Category:** User discussions\ **Tags:** forcefield, simulation-setup, topology\ **Created:** [December 11, 2024, 2:22pm UTC](https://gromacs.bioexcel.eu/t/chloroform-as-a-solvent-in-charmm36-force-field/10787 "2024-12-11T14:22:22Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![mehr](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/mehr/32/547_2.png) [@mehr](https://gromacs.bioexcel.eu/u/mehr)\ **Post date:** [December 11, 2024, 2:22pm UTC](https://gromacs.bioexcel.eu/t/chloroform-as-a-solvent-in-charmm36-force-field/10787/1 "2024-12-11T14:22:22Z")
GROMACS version: 2022.5 GROMACS modification: No I am interested in using chloroform (CHCl3) as a solvent instead of water in the Charmm36 force field. Unfortunately, I couldn’t find any topology for chloroform and since the atom types are not defined in Charmm36, gmx2gro is unable to generate the topology file. I wonder if anyone has used chloroform with this force field. Any help would be appreciated. ---
**Author:** ![mehr](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/mehr/32/547_2.png) [@mehr](https://gromacs.bioexcel.eu/u/mehr)\ **Post date:** [January 16, 2025, 12:57pm UTC](https://gromacs.bioexcel.eu/t/chloroform-as-a-solvent-in-charmm36-force-field/10787/2 "2025-01-16T12:57:45Z")
I found this .str file for chloroform (from here: [GitHub - ChayaSt/FFconversion: scripts to convert CHARMM files to OpenMM ffxml files](https://github.com/ChayaSt/FFconversion)) but when I use cgenff\_charmm2gmx\_py2.py to get the topology in Charmm36 ff, I face the error that the versions of CGenFF are not the same. I have CGenFF 2b8. How can I know by which version of CGenFF the .str file was produced? [chloroform.txt](https://gromacs.bioexcel.eu/uploads/short-url/uWUIs7qfd0ImhNTN0R90d6q5EFh.txt) (1.6 KB)