[DFTB-Plus-User] TD-DFTB

[Andrea Pedrielli]

Thank you very much for the answers,

Andrea

2017-01-23 12:13 GMT+01:00 Ben Hourahine <benjamin.hourahine at strath.ac.uk>:

> Hello Andrea,
>
> for extended states, TD-DFT can produce incorrect results. The
> implementation in DFTB 1.3 supports gamma point only k-point sampling of
> period systems, but the results will be unreliable if the excitations are
> 1) not local in nature or 2) have charge transfer-like character.
> Regards
>
> Ben
>
> On 23/01/17 08:21, Bálint Aradi wrote:
>
> Dear Andrea,
>
>
> Dear users, we are trying to compute the absorption spectra of
> core-shell SiC-SiO2 nanowires. We have the periodicity along the
> longitudinal direction and we suppose that there could be a charge
> transfer between the shell and the core. From the manual (footnote 5
> pag 46) it seems that this kind of problem is not tractable within
> current DFTB+ code implementation (1.3 Version). Is it true? Have
> you got any ideas about how we could treat this problem?
>
> Indeed, we do not have any periodic boundary condition for the TD
> extension in DFTB+ yet. As far as I am aware, periodic boundary
> conditions are somewhat questionable anyway when you do LDA/GGA based
> TD-DFT/B. And, as Jacek pointed out, DFTB does not deal with core
> electrons.
>
>   Best regards,
>
>   Bálint
>
>
>
>
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>
>
> --
>       Dr. B. Hourahine, SUPA, Department of Physics,
>     University of Strathclyde, John Anderson Building,
>             107 Rottenrow, Glasgow G4 0NG, UK.
>     +44 141 548 2325 <+44%20141%20548%202325>, benjamin.hourahine at strath.ac.uk
>
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