# CCL: Polarization Basis Functions

*From*: Grant Hill <Grant.Hill-x-glasgow.ac.uk>
*Subject*: CCL: Polarization Basis Functions
*Date*: Fri, 31 Aug 2012 21:09:52 +0100

Sent to CCL by: Grant Hill [Grant.Hill=glasgow.ac.uk]
Dear Gustavo,
The answer to this question strongly depends on the basis set in question. The
higher angular momentum functions DO contribute to the atomic energy in
correlated ab initio methods (such as CISD). A popular alternative for DFT or HF
based optimisations is to use symmetric homonuclear systems (often dimers). You
can find a more detailed answer in the original publication for any popular
basis set (e.g. correlation consistent for the former method, polarisation
consistent for the latter).
Best regards,
Grant
On 31 Aug 2012, at 19:47, "Gustavo L.C. Moura gustavo.moura*ufpe.br"
<owner-chemistry\a/ccl.net> wrote:
>
> 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. Moura
>
>