# Simulating protein with chromophore using amber forcefield

**URL:** <https://gromacs.bioexcel.eu/t/simulating-protein-with-chromophore-using-amber-forcefield/4080>\
**Category:** User discussions\
**Created:** [April 27, 2022, 10:12am UTC](https://gromacs.bioexcel.eu/t/simulating-protein-with-chromophore-using-amber-forcefield/4080 "2022-04-27T10:12:36Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![nandanhaloi123](https://avatars.discourse-cdn.com/v4/letter/n/e56c9b/32.png) [@nandanhaloi123](https://gromacs.bioexcel.eu/u/nandanhaloi123)\
**Post date:** [April 27, 2022, 10:12am UTC](https://gromacs.bioexcel.eu/t/simulating-protein-with-chromophore-using-amber-forcefield/4080/1 "2022-04-27T10:12:36Z")

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GROMACS version:  
GROMACS modification: No  
Here post your question  
Hello, I would like to prepare a system that contains protein with a chromophore and simulate using amber forcefield, all in gromacs. The system can be easily prepared using CHARMM-GUI if I chose to simulate with charmm, but not with amber forcefield. While this can be achieved using ambertools ([Cookie Absent](https://aip.scitation.org/doi/10.1063/5.0007630), [Amber Basic Tutorials - Tutorial A26](http://ambermd.org/tutorials/basic/tutorial5/)), it seems like same thing can also be done in gromacs (according to the JCP paper). Is there anyone aware of this?