Subject: Second negative frequency

From: "Ivan" <[email-masked]>
Date: Mon, 12 Feb 2001 00:42:42 +0100

Dear CCL'ers

I am working with programme GAMESS and an present time I am facing some
problems with TS.I am simulating H-transfer from NH3 bonded to the rest of
molecule to another "free" NH3 forming "free"NH4.
In TS there are two imaginary frequencies ( 1. - value about 975, that
correspond to H-transfer and 2.- value about 36 )  and  can't get rid of
this second little negative frequency. Firstly I tried to use keywords
PURIFY in $STATPT and $FORCE groups to purify hessian matrix but with no
results. Then I tried several approachs to find better TS, but all resulted
to the same TS. And IRC calculations in both directions are correct, because
according to IRC's this TS connects appropriate minimas on both side of the
hill.Finally I wanted to to perform IRC folowing the second negative
frequency, but GAMESS did not accept the specified frequency ( in $IRC
group ).

I would very appreciate any help,advice or trick.

Stanislav Ivan
student