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<DIV><FONT size=2>Hello Jia-lin,</FONT></DIV>
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<DIV><FONT size=2>The idea is not to neutralize the protein but the system to
avoid any</FONT></DIV>
<DIV><FONT size=2>artefactual behavior. This is even more important when using
PME. </FONT></DIV>
<DIV><FONT size=2>In general </FONT><FONT size=2>people add ions in the solvent
to get a net charge of zero. </FONT></DIV>
<DIV><FONT size=2>In your case it would be Chloride.</FONT></DIV>
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<DIV><FONT size=2>genion does that for gromacs.</FONT></DIV>
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<DIV><FONT size=2>Xavier</FONT></DIV>
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