<html>
<head>
<meta content="text/html; charset=ISO-8859-1"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
On 8/06/2012 1:09 PM, Sanku M wrote:
<blockquote
cite="mid:1339124986.25396.YahooMailNeo@web114403.mail.gq1.yahoo.com"
type="cite">
<div style="color:#000; background-color:#fff; font-family:times
new roman, new york, times, serif;font-size:12pt">
<div>Hi,</div>
<div> I am trying to use a table potential implementing
Weeks-Chandler-Anderson (WCA) interaction between a solute and
all atoms of a solvent like TIP3P water ( with nonzero
interaction in the Hydrogen atoms) . But, I am having a
trouble in specifying energy groups required for table
potential. </div>
<div>Here is the problem:</div>
<div> I have two atom types in water : OW and HW. and one atom
type in solute : POL</div>
<div><br>
</div>
<div>Now, I want to use two Table potentials with WCA
interactions between a) POL & HW and b) POL & OW </div>
<div>So, I created two table potential files: table_POL_HW.xvg
and table_POL_OW.xvg</div>
<div><br>
</div>
<div>and then</div>
<div>in the .mdp file, I specified </div>
<div>energygrps = POL OW HW </div>
<div>energygrps_table = POL OW POL HW</div>
<div><br>
</div>
<div>But, compiling the .mdp file using grompp ( version 4.5.4)
gives me following error</div>
<div>
<div>"Fatal error: </div>
<div>atoms 33 and 34 in charge group 1 of molecule type 'SOL'
are in different energy groups"</div>
<div><br>
</div>
<div>Clearly, using OW and HW as separate energy groups is
causing the problem.</div>
<div>So, I am looking for an option on how I can use the table
potential between solute and each atoms of solvent.</div>
<br>
</div>
</div>
</blockquote>
<br>
Energy groups can only be unions of complete charge groups. So your
energy groups require that you split the solvent charge group. The
solvent charge groups are defined in its [moleculetype]. Splitting
will mean that you will get integration artefacts at the cut-off
unless you use a proper long-ranged electrostatic method (i.e. an
Ewald family method).<br>
<br>
Mark<br>
</body>
</html>