# Non-Zero Total Charges in Simulation

**URL:** <https://gromacs.bioexcel.eu/t/non-zero-total-charges-in-simulation/6402>\
**Category:** User discussions\
**Tags:** grompp\
**Created:** [May 15, 2023, 6:46am UTC](https://gromacs.bioexcel.eu/t/non-zero-total-charges-in-simulation/6402 "2023-05-15T06:46:11Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Bratin](https://avatars.discourse-cdn.com/v4/letter/b/f07891/32.png) [@Bratin](https://gromacs.bioexcel.eu/u/Bratin)\
**Post date:** [May 15, 2023, 6:46am UTC](https://gromacs.bioexcel.eu/t/non-zero-total-charges-in-simulation/6402/1 "2023-05-15T06:46:11Z")

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# GROMACS version: 2018.8 GROMACS modification: No Dear all, I am trying to setup a poly-electrolyte system in aqueous medium with a total charge of 47.39 which can not be fully charge neutralised by adding counter-ions. Due to this reason I am getting following [note] and [warning]

NOTE 4 [file topol.top, line 65]:  
System has non-zero total charge: -0.397097  
Total charge should normally be an integer. See  
[Floating point arithmetic — GROMACS webpage https://www.gromacs.org documentation](http://www.gromacs.org/Documentation/Floating_Point_Arithmetic)  
for discussion on how close it should be to an integer.

# WARNING 2 [file topol.top, line 65]: You are using Ewald electrostatics in a system with net charge. This can lead to severe artifacts, such as ions moving into regions with low dielectric, due to the uniform background charge. We suggest to neutralize your system with counter ions, possibly in combination with a physiological salt concentration.

Please help me to decide whether I can proceed with -maxwarn flag or further charge assignment is necessary to obtain a charge neutralised system.  
Thank you