From owner-chemistry@ccl.net Sat Jun 15 23:26:01 2013
From: "Joseph Takayama sjtakayama(~)gmail.com" <owner-chemistry++server.ccl.net>
To: CCL
Subject: CCL:G: TS optimization help!
Message-Id: <-48829-130615222608-27499-irNF9CJ5flXG6+syao41SQ++server.ccl.net>
X-Original-From: "Joseph  Takayama" <sjtakayama_-_gmail.com>
Date: Sat, 15 Jun 2013 22:26:07 -0400


Sent to CCL by: "Joseph  Takayama" [sjtakayama*gmail.com]
Hi Everyone,

I'm trying to reproduce the TS structure optimization which is already 
reported in the paper.

First, I prepared the structures of the reactant and the product from the 
scratch and optimized them using the same basis functions as reported.
Obtained optimized structures seems similar to those reported and energy 
difference between reactant and product also matched to the value in the 
paper.

In order to obtain the TS structure, I first tried QST2 using optimized 
reactant and product structure. Didn't work out.

Some key bond lengths of the TS structure are also reported in the paper. 
So next, I freezed 2 key bond lengths using modredundant option and optimized 
the rest. 
Obtained structure seems quite similar to the TS structure in the paper.

> From that structure, I tried Opt=(ts, calcfc, noeigentest), with or without 
"tight" option and Opt=(QST3, calcfc). 
However, every time I tried, optimization goes to the structure far away from 
the TS structure that I want.

Is there any tips to lead the optimization to the TS structure that I want?
Or is there any options that prevents structure to go too far away from the 
initial structure?
I'm using Gaussian 09.

Any comment would be appreciated!

Joseph Takayama
sjtakayama(-)gmail.com