[Pw_forum] TiO2, ZO2 and BaTiO3 nanoclusters

[Giuseppe Mattioli]

Dear Andrey
Sorry for the late reply.

> I read the manual. So, need I take the parameters assume_isolated?

Yes, the Makov-Payne implementation of assume_isolated, e.g., provides decoupling of long-range electrostatic interaction between periodically 
replicated images of your clusters, as well as an estimate of the vacuum level, useful to the "absolute" alignment of band edges of different 
materials. It also works fine with the ENVIRON plug-in; if you are planning to perform calculations of charged clusters you may want to flick through 
the environ homepage here:

http://www.quantum-environment.org/

> I read the manual. So, need I take the parameters lda_plus_u?

Yes, but you should know what you are doing... Read carefully the DFT+U review papers, specially this one:

Himmetoglu et al International Journal of Quantum Chemistry 2014, 114, 14

For an interesting discussion about some limits of the simplified DFT+U approach in the case of TiO2 and ZnO you may flick through this paper:

Agapito et al Phys. Rev. X 5, 011006 2015
 
and for a "semiempirical" estimate of U in the cases of TiO2 and ZnO you may read my papers (for ZnO also the SuppInfo):

J. Phys. Chem. C 2012, 116, 15439
J. Phys. Chem. C 2014, 118, 29928

HTH
Giuseppe

On Wednesday, March 23, 2016 12:23:22 PM Andrey Chibisov wrote:
> Dear Colleagues!
> I have some questions.
> I want to calculate the electronic structure of the TiO2, ZO2 and BaTiO3 nanoclusters and get good value of bandgap.
> I read the manual. So, need I take the parameters assume_isolated and lda_plus_u?
>  
> -- 
> Best regards,
> Andrey Chibisov. Ph.D.
> Numerical method of mathematical physics Laboratory,
> Computational Center, Russian Academy of Sciences.
> Khabarovsk, Russia
> Web page: https://www.researchgate.net/profile/A_Chibisov
> http://ru.linkedin.com/pub/andrey-chibisov/55/253/986/en

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   Giuseppe Mattioli                            
   CNR - ISTITUTO DI STRUTTURA DELLA MATERIA   
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