CCL: Gaussian - partial optimization



 Sent to CCL by: "d w" [wangdq2100|"|hotmail.com]
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 hi,
 
i didn't ever do such calculations, so my advice here is only for your reference and not sure it works:
 
1. if your molecule is not so large, try using "modredun" to fix the part as your want; 2. if molecule is too large, the method seems stupid. i remember there is a "constant" part in gaussian input file following "variable" part. so pls. prepare your input structure in the form of internal coordinate and move the parameter of the part you want to fix to the "constant" block. maybe you need care the ordering of the atoms in your molecule.
 good luck.
 wang
 
 From: "CCL" <owner-chemistry|"|ccl.net>
 Reply-To: "CCL Subscribers" <chemistry|"|ccl.net>
 To: "Wang, Dongqi " <wangdq2100|"|hotmail.com>
 Subject: CCL: Gaussian - partial optimization
 Date: Mon, 19 Sep 2005 14:48:32 +0200
 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?