# Umbrella Sampling and Protein-Ligand Complex using Chemical Ligand? **URL:** \ **Category:** User discussions\ **Created:** [December 5, 2020, 11:51am UTC](https://gromacs.bioexcel.eu/t/umbrella-sampling-and-protein-ligand-complex-using-chemical-ligand/1203 "2020-12-05T11:51:06Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![mjsubach](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/mjsubach/32/387_2.png) [@mjsubach](https://gromacs.bioexcel.eu/u/mjsubach)\ **Post date:** [December 5, 2020, 11:51am UTC](https://gromacs.bioexcel.eu/t/umbrella-sampling-and-protein-ligand-complex-using-chemical-ligand/1203/1 "2020-12-05T11:51:06Z")
GROMACS version: 2020.3 GROMACS modification: Yes/No Here post your question: Is it possible to perform Umbrella Sampling and Protein-Ligand Complex Analysis using a Chemical (CBX) Ligand in lieu of a protein? Thanks:) Joel ---
**Author:** ![cblau](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/cblau/32/5_2.png) [@cblau](https://gromacs.bioexcel.eu/u/cblau)\ **Post date:** [December 7, 2020, 10:13am UTC](https://gromacs.bioexcel.eu/t/umbrella-sampling-and-protein-ligand-complex-using-chemical-ligand/1203/2 "2020-12-07T10:13:13Z")
Hi, Yes, that’s all possible - there is nothing specific to being a protein in GROMACS, when it comes to umbrella sampling; as long as you can define a group of atoms for the thing that you want to pull, you are good to go. ---
**Author:** ![mjsubach](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/mjsubach/32/387_2.png) [@mjsubach](https://gromacs.bioexcel.eu/u/mjsubach)\ **Post date:** [December 7, 2020, 10:24am UTC](https://gromacs.bioexcel.eu/t/umbrella-sampling-and-protein-ligand-complex-using-chemical-ligand/1203/3 "2020-12-07T10:24:58Z")
Hi cblau ok and thank you for your kind update.:)