[DFTB-Plus-User] information of basis functions and confinement potential

[Iresh Shamika]

I am a novice and I have been trying to do a geometry optimization on
fulgides molecules in solid state.So far I have been making it as geometry
is converge but unfortunately it has not like that.Please help to over come
from this .Also I could not find out the best values for K point
calculation .

On Thu, Apr 9, 2015 at 10:43 PM, 张文星 <zhangwenxing at tyut.edu.cn> wrote:

> Dear Gao,
> You are welcome. Right, the basis functions are not available in the SK
> files.
> LCAO method only guarantees you could use a parameterized model
> Hamiltonian to reproduce the band structure of solid.
> But we have no idea about the exact appearance of the basis used because
> it is necessary only when we want to
> check the physics of the basis for example we develop one tigh binding
> model. Otherwise, if you need to calculate some kind
> of properties then just calculate it with respect to your band
> structure like the DFT do. If you need to derive some kind of formula
> which include the basis function, then you have to transform your formula
> into terms of Hamiltonian matrix element or Overlap
> matrix element, then you can calculate them. Or you really need the exact
> appearance of the basis function, then atomic orbital
> is one choice, but you need to get out the relationship between the matrix
> elements in H and the electronic integral with respect
> to the atomic orbital. Pherhaps, wannier function should be a better
> choice than atomic orbital. I could not to offer more help on
> your question because I have not got out any basis function for tight
> binding model until now, and it is not necessary in my study.
> best,
> Zhang
>
> ---------- Origin message ----------
> >From："Gao Bin" <bin.gao at uit.no>
> >To："User list for DFTB+ related questions" <
> dftb-plus-user at mailman.zfn.uni-bremen.de>
> >Subject：Re: [DFTB-Plus-User] information of basis functions and
> confinement potential
> >Date：2015-04-09 21:46:45
>
>
>
> Dear Zhang,
>
>
>
> Thank you for your reply. Actually, I found some published atomic basis
> functions at http://www.dftb-plus.info/tools/waveplot/ (angular momentum,
> exponents and coefficients). As you may notice, different SK sets can use
> different atomic basis functions, that are not available in the SK files.
>
>
>
> My question, if I rephrase, is that how one can get these basis functions
> (angular momentum, exponents and coefficients) and the confinement
> potential (or the wave function compression radius if harmonic potential
> used, see eq. (4) in J. Chem. Theory Comput. 2013, 9, 338). These are
> important for post-processing after the DFTB calculations.
>
>
>
> Cheers
>
> Gao
>  ------------------------------
> *From:* dftb-plus-user-bounces at mailman.zfn.uni-bremen.de <
> dftb-plus-user-bounces at mailman.zfn.uni-bremen.de> on behalf of 张文星 <
> zhangwenxing at tyut.edu.cn>
> *Sent:* Thursday, April 9, 2015 4:06 AM
> *To:* User list for DFTB+ related questions
> *Subject:* Re: [DFTB-Plus-User] information of basis functions and
> confinement potential
>
>  Dear Gao,
> The sk files include only the parameters used in the formulated
> Hamiltonian and Overlap matrix.
> The two matrix are well formulated according to the tight binding model
> and the basis functions
> are atom or atomlike orbitals which you can refer to the original Slater
> Koster paper in physical review about 60 years ago.
> best wishes,
> Zhang
>
> ---------- Origin message ----------
> >From："Gao Bin" <bin.gao at uit.no>
> >To："User list for DFTB+ related questions" <
> dftb-plus-user at mailman.zfn.uni-bremen.de>
> >Subject：[DFTB-Plus-User] information of basis functions and confinement
> potential
> >Date：2015-04-09 01:22:25
>
>
> Dear all,
>
>
>
> I have a question regarding the DFTB parameters, or the Slater-Koster
> files, from which we will know for instance the matrix elements of overlap
> and Hamiltonian.
>
>
>
> But how could we know the basis functions (the coefficient, angular
> number, exponent, see for example eq.(3) in J. Chem. Theory Comput. 2013,
> 9, 338) and the confinement potential (or the wave function compression
> radius if harmonic potential used, see eq. (4) in J. Chem. Theory Comput.
> 2013, 9, 338)? Do we have to read the original literature? Or is it
> possible to find such information in the parameter files? Thank you in
> advance.
>
>
>
> Cheers
>
> Gao
>
> _______________________________________________
> DFTB-Plus-User mailing list
> DFTB-Plus-User at mailman.zfn.uni-bremen.de
> https://mailman.zfn.uni-bremen.de/cgi-bin/mailman/listinfo/dftb-plus-user
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.zfn.uni-bremen.de/pipermail/dftb-plus-user/attachments/20150413/c465c797/attachment.htm>