[gmx-users] System has non-zero total charge: 2.570000e+00

[Itamar Kass]

Justin A. Lemkul wrote:
>
>
> najwa drici wrote:
>> hello Gromacs users,
>> I have some problems about the total charge of system using Gromacs.
>> I wanted to perform molecular dynamic simulation in box of SPC water.  
>> before energy minimization step , I performed the preprosessing step 
>> using grompp  . However, there’s a note that : System has non-zero 
>> total charge: 2.570000e+00 “.
>> why the total charge of system is not an integer?
>
> Something is broken.  Check the topology to see what is causing the 
> non-integral charge.  If you want any other help, you'll have to 
> describe what you're doing in much greater detail.
>
> -Justin
>
>> thank you
>> nejoua DRICI
>>
>> ------------------------------------------------------------------------
>> Messenger débarque dans Hotmail ! Essayez-le ! 
>> <http://www.windowslive.fr/hotmail/web-messenger/>
>>
>>
>> ------------------------------------------------------------------------
>>
>> _______________________________________________
>> gmx-users mailing list    gmx-users at gromacs.org
>> http://lists.gromacs.org/mailman/listinfo/gmx-users
>> Please search the archive at http://www.gromacs.org/search before 
>> posting!
>> Please don't post (un)subscribe requests to the list. Use the www 
>> interface or send it to gmx-users-request at gromacs.org.
>> Can't post? Read http://www.gromacs.org/mailing_lists/users.php
>
Hi,

If you have non water molecule in the box (eg protein) their charge 
might differ from 0. SO you might add ions in order to neutralize it.

Best,
Itamar