<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta content="text/html; charset=ISO-8859-1"
http-equiv="Content-Type">
</head>
<body text="#000000" bgcolor="#ffffff">
On 06/27/2011 07:31 PM, Mr Bernard Ramos wrote:
<blockquote
cite="mid:1309167088.65718.YahooMailClassic@web161504.mail.bf1.yahoo.com"
type="cite">
<table border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td style="font: inherit;" valign="top">Hi!
<div><br>
</div>
<div>I would like to freeze two dihedrals/torsion angles
but allow the rest (i.e. bonds, angles) to relax during
energy minimization and MD. How do I go over applying
constraints? Thanks.</div>
</td>
</tr>
</tbody>
</table>
</blockquote>
<br>
See <a
href="http://www.gromacs.org/Documentation/Terminology/Constraints_and_Restraints">http://www.gromacs.org/Documentation/Terminology/Constraints_and_Restraints</a>
to sort out some nomenclature. You probably want a dihedral
restraint with a strong force constant (though other approaches are
possible). See relevant parts of chapters 4 and 5. Work by analogy
from the [dihedrals] and [position_restraints] sections in your
existing [moleculetype].<br>
<br>
Mark<br>
</body>
</html>