CCL:G: TS optimization help!

 Sent to CCL by: Errol Lewars [elewars:-:trentu.ca]
 2013 June 16
 "In order to obtain the TS structure, I first tried QST2 using optimized
 reactant and product structure. Didn't work out".
 QST2 is said to work better if instead of using as input the *optimized*
 reactant and product you distort each toward the other, i.e toward the
 transition state.
 You might also try taking one of the two minima and doing a scan, altering a
 geometric parameter in the TS direction; then submitting the highest point on
 the IRC-like curve (assuming you get such a curve) to a TS optimization/freq.
 E. Lewars
 ==
 Joseph Takayama sjtakayama(~)gmail.com wrote:
 
 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>