Subject: CCL:G:BhandhLYP

From: [email-masked] (Joe Durant)
Date: Mon, 27 Jan 1997 07:54:20 -0800 (PST)

Hi John!

You asked about the status of Becke's half and half functional, as
implemented by Gaussian.  I am mainly concerned with calculating
transition states, and find that it is the only functional
implemented by Gaussian that does not systematically underpredict
barrier heights.

You are correct in noting that Gaussian's implementation is not in
keeping with Becke's; I would be interested in knowing how well
Gaussian's implementation performs on the "G2 set" of
molecules. (I would be grateful to anybody who forwards me a set of
z-matrices for these molecules!). 

Gaussian eliminated the option in the first couple of releases of G94
(although you can still specify it explicitly); they recanted and have
reinstated it in the more recent releases.
 
In summary, BHandHLYP seems to have some advantages; while not perfect
it is my first choice for calculating transition state properties.

Joe

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