[DFTB-Plus-User] Error in installation

[Bálint Aradi]

Dear Akanksha,

> pdos and band structure of TiO2 as given in the recipe. Sir, I am able
> to generate the pdos and dos results. But I am getting only one weird
> line as my band structure. I am a new user to dftb+ and I kept the file
> as it is but only changed the path for the slako file. I unable to
> understand why it is happening so and even unable rectify the problem,
> the output is generated without any error, but I am getting warning in
> output file as

If the DOS and PDOS are fine, that means your first calculation (the one
producing the proper density) is OK.

> WARNING!
> -> SCC is NOT converged, maximal SCC iterations exceeded. I am unable to
> understand why it is giving this warning because i have already copied
> the converged charges in the working directory as charge.bin.
> I have attached the plot of od and pdos as well as the weird band
> structure of TiO2. I would be thankful for all your suggestions.

When you calculate the band structure, you have a very bad k-point
sampling as you typically sample only the high-symmetry lines.
Therefore, you do not want to reach convergency in the charges in that
calculation. You rather:

- read in the charges from the first calculation (with the good k-point
sampling)
- build all the Hamiltonians in your highly symmetric k-points
- diagonalize them to get the band structure
- and stop-

In DFTB+, you can reach that by setting

ReadInitialCharges = Yes
MaxSccIterations = 1

The warning about exceeding the amximal (1) SCC iterations can be
ignored in that case, as you did not want to reach convergence anyway in
this case.

If your band structure is flat, than maybe your k-points are not defined
correctly for the band structure calculation?

Best regards,

Bálint

-- 
Dr. Bálint Aradi
Bremen Center for Computational Materials Science, University of Bremen
http://www.bccms.uni-bremen.de/cms/people/b-aradi/


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