Re: [Phonopy-users] Phonopy Aluminium calculation

[Eric H. <er...@vi...>]

Hi Professor Togo,
Most definitely, I would not want to read it either.  I am not as concerned that my code is wrong, rather that I have inappropriate values or a missing step.  Here are the 5 main parts:
1. Line 18-27 define the inputs for my PWScf file:
• PrimMatrix = [[0.0, 0.5, 0.5], [0.5, 0.0, 0.5], [0.5, 0.5, 0.0]]
• DIM = [[3,0,0], [0,3,0], [0,0,3]]
• input_dft = 'PBE'
• ecutwfc = 40
• smearing = 'methfessel-paxton'
• degauss = 0.10
• k_pnt_grid = '9 9 9'
I checked convergence for these parameters in a 2x2x2 cell, and they seemed more than adequate.
2. I then create supercells (these files looked fine) and run the PWScf calculation.
3. Line 152 collects the forces from the PWScf file, and line 155 assigns them to the phonon object (same as the command line).
4. Line 164 and 166 creates and symmetrize the force constants.
5. Two different dispersions are plotted in lines 190-196 or 197-203. They are for the same system, the only difference is that one contains path W[ ½  ¼ 0]-X [ ½  0 0]-Γ[0 0 0] the other contains path W[ ½  ¼ 0]-X*[ ½ ½ 0]-Γ[0 0 0].

Thank you for any help you may provide,
Eric Hoglund
Graduate Research Assistant
University of Virginia

From: Atsushi Togo
Sent: Wednesday, September 20, 2017 9:49 PM
To: phonopy-users
Subject: Re: [Phonopy-users] Phonopy Aluminium calculation

Hi,

- I don't want to read your script from top to bottom. You can point
out which part is important.
- I don't see how the band structures are generated. What is the
difference of the calculations between them?

Togo

On Mon, Sep 18, 2017 at 1:06 AM, eric hoglund <er...@vi...> wrote:
> Dear phonopy community,
>
>
> I recently began using Phonopy in conjunction with Quantum Espresso to
> calculate the phonon dispersion of aluminum, and plan to carry this forward
> into aluminum grain boundaries.  I would like to achieve the correct
> dispersion for bulk aluminum before I begin on the more complex boundaries.
> I have tried running a similar simulation to the one mentioned in the
> Phonopy paper:
>
> 3x3x3 supercell
> ecutwfc=40
> kgrid=9 9 9
> smearing = 'methfessel-paxton'
> degauss = 0.05
>
> I collect the forces from the output file, create the force constants,
> symmetrize_force_constants_by_space_group, then proceed to calculate the
> phonon dispersion. I 100% agree with the phonon dispersion of the paper, but
> can not get mine to match. I have attached both my python script and the
> resulting dispersion. The python script generates the “.in” files for QE and
> runs all of the Phonopy calculations. The dispersion is clearly off at the
> W&K points, there shouldn’t be any gap between bands 2&3. Attached are the
> python script, and two dispersion (just different symmetry points).
>
> To make life easier, here is the link to the Phonopy paper:
> https://arxiv.org/pdf/1506.08498.pdf.
>
> Any thoughts would be much appreciated, and amazing software!
>
>
>
> Thank you for any help you may provide,
>
> Eric Hoglund
>
> Graduate Research Assistant
>
> University of Virginia
>
>
> ------------------------------------------------------------------------------
> Check out the vibrant tech community on one of the world's most
> engaging tech sites, Slashdot.org! http://sdm.link/slashdot
> _______________________________________________
> Phonopy-users mailing list
> Pho...@li...
> https://lists.sourceforge.net/lists/listinfo/phonopy-users
>



-- 
Atsushi Togo
Elements Strategy Initiative for Structural Materials, Kyoto university
E-mail: atz...@gm...

------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
_______________________________________________
Phonopy-users mailing list
Pho...@li...
https://lists.sourceforge.net/lists/listinfo/phonopy-users