[Pw_forum] DFT+U calculations

[Muhammad Adnan]

Dear Mostafa
Thanks for pointing out my mistake in the title of the email.
Actually, I need to compute DeltaG, DeltaH and DeltaST for the reaction,
TiO2 --> TiO2-1 + 1/2O2.
for this, i need vibrational frequencies of TiO2 and TiO2-1. If relax the
surfaces with DFT+U and then use simply DFT calculations for calculating
frequencies, what would be the effect on frequencies?

On Wed, Aug 12, 2015 at 8:02 PM, Mostafa Youssef <myoussef at mit.edu> wrote:

> Hi Adnan,
>
>
> The effect of DFT+U on the phonon dispersion of materials with soft-modes
> such as TiO2 is large. Not only quantitatively but also qualitatively.  See
> for example:
>
> http://www.sciencedirect.com/science/article/pii/S1567173910004682
>
>
> and figure 8 in:
>
> http://iopscience.iop.org/0953-8984/26/12/122203/
>
>
> If your main goal is to study phonons of TiO2 , I would recommend LDA or
> PBEsol.  But if you insist on using DFT+U , then you can use PHONOPY +
> PWscf code of Q.E equipped with a *large* supercell of TiO2.  This should
> allow you to calculate phonon dispersion in frozen phonon approximation
> with Parlinski et al interpolation.  Please follow the instructions on
> PHONOPY website.
>
>
> Mostafa YOussef
> MIT
> P.S. Somehow I read the title of your thread as DFT+U cartoons !
>
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-- 
Best Regards
Muhammad Adnan Saqlain
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