Re: CCL:Frequency calculation of transition state

["Peter Shenkin" <shenkin - at - still3.chem.columbia.edu>]

 On Aug 28, 10:57pm, patrick wrote:
 > Subject: CCL:Frequency calculation of transition state
 >
 >
 >
 > Hi!  How are you?  During computation of frequency of molecules at
 > transition state, one of frequencies is negative.  Why?  Is it a rule for
 > identification of transition state?  Is it possible if two or more
 > frequencies are negative when molecules are at transition state?
 >
 > Thank you for your attention.
 As others will no doubt tell you, this has to do with the definition
 of a transition-state as a saddle-point on the potential-energy
 surface, and to the mathematical definition of a saddle point.
 This goes back to Henry Eyring (at least) and his theory of the
 activated complex.
 Certainly extrema with two or more negative "frequencies" are
 geometrically possible;  I don't know exactly what their chemical
 significance, if any, would be, or how many, if any, have actually been
 identified.  I know people have thought about this and even looked
 into it, and perhaps some who know will respond here.
 	-P.
 --
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