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<P><FONT SIZE=2>-----Original Message-----<BR>
From: gmx-users-bounces@gromacs.org on behalf of X.Periole<BR>
Sent: Wed 6/28/2006 7:29 PM<BR>
To: Discussion list for GROMACS users<BR>
Subject: Re: [gmx-users] How do Charge Groups work?<BR>
<BR>
>> I had a system where I have no charges in it, but I do<BR>
>>have Lennard-Jones non-bonded interactions. I've noticed<BR>
>>that I get different values for the Lennard-jones<BR>
>>interaction energy differs depending how I split the<BR>
>>system up into charge groups (as the charge group concept<BR>
>>is kinda abitrary in a system with no charges), this can<BR>
>>not be right surely?<BR>
>><BR>
>> As I understood it the charge groups were used to help<BR>
>>compile the neighbour lists, but what I want is all the<BR>
>>atoms within my cut-off radius to be in my pair-list (for<BR>
>>that atom). Is there an option to ignore the charge<BR>
>>groups? I find I get bigger Lennard-Jones interactions if<BR>
>>I put my whole system into a charge group that if I split<BR>
>>it up, but I need to split it up for my larger systems.<BR>
>>Is there a way to increase the maximum number of charge<BR>
>>groups? And is this a good idea?<BR>
<BR>
>>You should check the manual for the option allowing a atom<BR>
>>base cutoff, I am not sure it actually exist.<BR>
>>A crude way to fix it would be to define each atom as a<BR>
>>seprate charge group.<BR>
<BR>
Hi Xavier, thanks for the help.<BR>
<BR>
I tried putting all the atoms in different charge groups, but then I get no Lennard-Jones' Interactions. I'm using a cut-off potential and my Lennard-Jones interactions are included as type 1 interactions with combination rule 1. Any ideas?<BR>
<BR>
Ella<BR>
<BR>
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