[DFTB-Plus-User] TD-DFTB

Ben Hourahine benjamin.hourahine at strath.ac.uk
Mon Jan 23 12:13:12 CET 2017

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.



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,
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