Subject: Basis sets.

From: Brian Salter-Duke <[email-masked]>
Date: Tue, 15 Feb 2000 08:02:43 +0930

I have a comment and a request leading from it. Increasingly I read about 
basis sets such as 6-31G for 3rd row atoms, 6-311G for transition 1st row 
metals. These of course are not strictly 6-31G and 6-311G. We have the 
Binning-Curtiss basis fro Ga-Kr, and the Maclean-Chandler basis for 2nd row
which are both labelled 6-31G. The 6-311G basis for transition metals is 
the Wachters basis. G2 for Ga-Kr uses another basis which is labelled
6-311G. This is unfortunate. The correct name should be used. It also
clouds my question in that it leads people to believe that say the proper 
Pople 6-31G for F is, in some sense, equivalent to the McLean-Chandler basis
for Cl. My question is this - what criteria could we use to test whether
a basis set for one row is equivalent to a basis set for another row?

I have thought hard about this and can not come up with a satisfactory answer.
You might say it is meaningless and so it is in a sense. But in developing
say G2 theory or G3 theory for a set of elements where it has not previously
been used one has to address it by selecting basis sets that are in some 
sense equivalent to those used in the theory previously for other atoms.
Thus Curtiss and coworkers developed the basis used for Ga-Kr and labelled it
6-311G, but it is actially, from memory, [62111111,3331111,41].

I will post a summary of responses.

Regards, Brian Duke.
-- 
        Associate Professor Brian Salter-Duke (Brian Duke)
Chemistry, Faculty of Science, IT and Education, Northern Territory University,
          Darwin, NT 0909, Australia.  Phone (61) (0)8-89466702
e-mail: [email-masked]  or [email-masked]