# CCL: Polarization Basis Functions

*From*: "Van Dam, Hubertus J"
<HubertusJJ.vanDam]~[pnnl.gov>
*Subject*: CCL: Polarization Basis Functions
*Date*: Fri, 31 Aug 2012 12:56:37 -0700

Sent to CCL by: "Van Dam, Hubertus J" [HubertusJJ.vanDam|*|pnnl.gov]
Hi Gustavo,
I think the simple answer is that you are right if you want to optimize the
exponents with an effective 1-electron model. However, when you introduce
electron correlation (i.e. some kind of CI treatment) then the
"unoccupied" d and f's do contribute. I think you might find some
information that is useful on this point in the papers that discuss the creation
of ANO (Atomic Natural Orbital) basis sets.
I hope this helps,
Huub
-----Original Message-----
> From: owner-chemistry+hubertus.vandam==pnnl.gov===ccl.net [mailto:owner-chemistry+hubertus.vandam==pnnl.gov===ccl.net]
On Behalf Of Gustavo L.C. Moura gustavo.moura*ufpe.br
Sent: Friday, August 31, 2012 11:48 AM
To: Van Dam, Hubertus J
Subject: CCL: Polarization Basis Functions
Sent to CCL by: "Gustavo L.C. Moura" [gustavo.moura~!~ufpe.br] Dear
CCL Readers,
How are the exponents of the polarization functions determined in a basis set?
Taking carbon as an example, I know that we may determine the exponents of the
s and p basis functions through the minimization of the electronic energy of an
atomic calculation. But, how to determine the exponents of the d, or even f,
basis functions if they do not contribute to the energy of the isolated atom?
I apologize if this question sounds too basic, but I failed to find an answer
to this question in the internet or in my books.
Thank you very much in advance for helping me with this question.
Sincerely yours,
Gustavo L.C. Mourahttp://www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp-:-//www.ccl.net/chemistry/sub_unsub.shtmlhttp-:-//www.ccl.net/spammers.txt