Subject: excited states and basis sets

From: Michael Nolan <[email-masked]>
Date: Thu, 22 Jul 1999 20:59:53 +0100

Hi CCLers

I have a question which might of interest to the community at large.
In our group a CI programm has been developed and the ultimate
aim of this programm is to look at defect states in semiconductors.
Before we can do this we have to see if the programm works!

So we are looking at excited states of the silicon atom.
The main problem we have is the lack of literature on systematic
studies of basis sets and excited states.  A search of the ISI database
from 1990 gave nothing useful, except that people are using the standard
aug-cc-pVTZ basis set of Dunning. For our computational capacity
this is rather too big (59 basis functions).
Having experimented ourselves a little we have come to the conclusion that a DZ
basis is better than a TZ basis, that polarisation functions are very important
but that the addition of Rydberg functions and *standard* diffuse functions
is not so important. Thus we found Dunning's VDZ + polarisation and 6-31G* 
are quite useful. 
So, is anyone else looking at this area? 
We are also wondering if we should try and obtain diffuse exponents ourselves
or is anyone again looking at this?

Thank you for your patience

Michael
-- 
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Mr. Michael Nolan BSc. MEngSc.	
Materials Modelling Section, Advanced Materials and Technologies Group
National Microelectronics Research Centre  	
Lee Maltings, Prospect Row				   	
Cork, IRELAND

mail: [email-masked]
Tel:   + 353 21 904113; Fax: +353 21 270271

http://nmrc.ucc.ie/groups/AMT/modellingRes.html
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