# Topology file for SCN anion for opls force field

**URL:** <https://gromacs.bioexcel.eu/t/topology-file-for-scn-anion-for-opls-force-field/7085>\
**Category:** User discussions\
**Created:** [August 26, 2023, 11:25am UTC](https://gromacs.bioexcel.eu/t/topology-file-for-scn-anion-for-opls-force-field/7085 "2023-08-26T11:25:22Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![710](https://avatars.discourse-cdn.com/v4/letter/7/34f0e0/32.png) [@710](https://gromacs.bioexcel.eu/u/710)\
**Post date:** [August 26, 2023, 11:25am UTC](https://gromacs.bioexcel.eu/t/topology-file-for-scn-anion-for-opls-force-field/7085/1 "2023-08-26T11:25:22Z")

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GROMACS version:2022.04  
GROMACS modification: No  
I need to create topology file for SCN anion using opls force field.but parameters for anion is not given in opls. How to create it.

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**Author:** ![Karis](https://avatars.discourse-cdn.com/v4/letter/k/ed8c4c/32.png) [@Karis](https://gromacs.bioexcel.eu/u/Karis)\
**Post date:** [August 28, 2023, 8:35am UTC](https://gromacs.bioexcel.eu/t/topology-file-for-scn-anion-for-opls-force-field/7085/2 "2023-08-28T08:35:17Z")

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Have you tried using Ligpargen ([LigParGen Server](http://zarbi.chem.yale.edu/ligpargen/))?