# Conformational energy for free ligand

**URL:** <https://gromacs.bioexcel.eu/t/conformational-energy-for-free-ligand/3281>\
**Category:** User discussions\
**Created:** [December 10, 2021, 2:49pm UTC](https://gromacs.bioexcel.eu/t/conformational-energy-for-free-ligand/3281 "2021-12-10T14:49:59Z")\
**Posts on this page:** 1\
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**Author:** ![alevilla](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/alevilla/32/439_2.png) [@alevilla](https://gromacs.bioexcel.eu/u/alevilla)\
**Post date:** [December 14, 2021, 9:28am UTC](https://gromacs.bioexcel.eu/t/conformational-energy-for-free-ligand/3281/2 "2021-12-14T09:28:26Z")

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Hi,  
You did not specify the setting but I guess that you have a ligand in water+ion solution, you use PME to describe long range electrostatic and you use a force field that require DispersionCorrection.  
Note, that not always energy decomposition is possible. For example if you use PME to describe the long you can not decompose the energy.

see [How to decompose enthalpic components using the group energy exclusion scheme?](https://gromacs.bioexcel.eu/t/how-to-decompose-enthalpic-components-using-the-group-energy-exclusion-scheme/1728)

Best regards  
\Alessandra

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