G:Sn2reaction
Hi CCL'ers.
I'm trying to calculate TS for one Sn2 reaction. As starting point I used
AB..C
where AB was optimised as adduct and C as pure substance.
As I know product is A..BC (known from molecular dynamics in best chemical
computer called "Schlenkflask with periodicbox 25 ml filled with npentan
molecules, run time 5 min").
I've tried to change primary distance B...C but what I'm becoming is
AB..C with very big B..C distance or if B..C was short A..BC with veeeery
long A..B distance.
What I've tried was three jobs:
1. opt=(zmatrix,TS)
answer:
 Wrong number of Negative eigenvalues: Desired= 1 Actual= 0
2. opt=(zmatrix,Saddle=2)
answer:
 Wrong number of Negative eigenvalues: Desired= 2 Actual= 0
3. opt=(zmatrix)
answer: after useing all possible steps how I wrote above one of two A..B
or B..C distances going in direction infinity
Maximum Force 0.000143 0.000450 YES
RMS Force 0.000076 0.000300 YES
Maximum Displacement 0.248104 0.001800 NO
RMS Displacement 0.044904 0.001200 NO
Can somebody tell me how to make Gaussian to do it?
thanks in advance
Krzys Radacki
_________________________
 email: Krys.Radacki()at()ac.RWTHAachen.DE


