From owner-chemistry@ccl.net Mon Sep 19 10:14:38 2005
From: "CCL" <owner-chemistry[]server.ccl.net>
To: CCL
Subject: CCL: Gaussian - partial optimization
Message-Id: <-29226-050919101244-23195-9HGAgNGX9ipmoLHTCIgmKw[]server.ccl.net>
X-Original-From: Joslyn Y Kravitz <jyudenfr[]umich.edu>
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Date: Mon, 19 Sep 2005 10:12:35 -0400 (EDT)
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Sent to CCL by: Joslyn Y Kravitz [jyudenfr[]umich.edu]

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You should define your coordinates using internal rather than cartesian 
coordinates. If you define the distance between the molecules as one of 
the bond lengths then you can freeze that bond length and the two 
molecules should stay put. In fact, you can freeze all coordinates except 
for the atoms in the hydroxyl groups.

Joslyn Kravitz




On Mon, 19 Sep 2005, CCL wrote:

> Hi,
> I'm trying to establish a mutual orientation of two hydroxyl groups in
> a dimeric system  (Gaussian).
> Unfortunately, when I perform a partial optimization of these groups the
> relative distance beetwen two molecules is also changing.
> What could be done to optimize only hydroxyls while keeping the rest of
> the system in its initial coordinates?