# Minimization with flexible water in Charmmff

**URL:** <https://gromacs.bioexcel.eu/t/minimization-with-flexible-water-in-charmmff/9583>\
**Category:** User discussions\
**Created:** [July 5, 2024, 2:47pm UTC](https://gromacs.bioexcel.eu/t/minimization-with-flexible-water-in-charmmff/9583 "2024-07-05T14:47:09Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Nik](https://avatars.discourse-cdn.com/v4/letter/n/6de8d8/32.png) [@Nik](https://gromacs.bioexcel.eu/u/Nik)\
**Post date:** [July 5, 2024, 2:47pm UTC](https://gromacs.bioexcel.eu/t/minimization-with-flexible-water-in-charmmff/9583/1 "2024-07-05T14:47:09Z")

</div>

GROMACS version: 2023.3  
GROMACS modification: No

I tried to run energy minimization. But I get notice: One or more water molecules can not be settled.  
I than done minimization of the system with md parameter define -DFLEXIBLE and minimization was fine. In order to prepare system to molecular dynamics I than run a second round of minimization with rigid water. Nevertheless, second found of minimization stops at 10-15 steps because systems reaches the Fmax \< 1000.  
Is it enough to have only 10-15 steps in the minimization with rigid water, or it is necessary to continue second round of minimization in order to prepare system for molecular dynamics?