[Wien] Wien Digest, Vol 113, Issue 6 - 20. Phonon Calculation

[Madesis Ioannis(John)]

On 2015-04-22 15:14, wien-request at zeus.theochem.tuwien.ac.at wrote:
> 
> Message: 20
> Date: Tue, 21 Apr 2015 23:12:14 +0300
> From: "Madesis Ioannis(John)" <imadesis at physics.uoc.gr>
> To: wien at zeus.theochem.tuwien.ac.at
> Subject: [Wien] Phonon calculation
> Message-ID: <ee9ef72b64b814badcbadb4743aab61e at imap.physics.uoc.gr>
> Content-Type: text/plain; charset=UTF-8; format=flowed
> 
> Hello
> 
> I am running some calculations using the phonopy software, and I had
> this idea-question. For example, I run the YBCO6.5, with 25 different
> displacements, w?th the corresponding 25 *.struct files. My question
> would be the following:
> Assuming I have just completed the run for the first displacement. Is
> there a way to transfer my converged data to the NEXT structure (plane
> waves+ orbitals), in order to minimize the number of iterations for the
> SCFs to come? I understand that it might be risky, however it would
> (probably) lead to a much faster convergence for the rest of the
> structures.
> 
> Message: 21
> Date: Tue, 21 Apr 2015 22:20:54 +0200
> From: Peter Blaha <pblaha at theochem.tuwien.ac.at>
> To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at>
> Subject: Re: [Wien] Phonon calculation
> Message-ID: <5536B126.7010806 at theochem.tuwien.ac.at>
> Content-Type: text/plain; charset=utf-8; format=flowed
> 
> Yes, something like this can be done and saves some time. But you need
> to be sure that
> the symmetry for all these cases are the same.
> 
> If you make + and - displacments, you can be sure that these two 
> structures
> have the same symmetry.
> 
> The same is true for all structures with P1 symmetry, but this needs
> manual inspection.
> 
> What you can copy are the scf-densites, i.e.
> 
> cp case_1/case_1.clmsum  case_2/case_2.clmsum
> 
This is why I specified that I work with phonopy. Phonopy, (if you don't 
already know) requires all generated structures to be of P symmetry. To 
be honest, this is not always possible since I cannot override Wien2K 
algorith, which detects possible symmetries (initialization runs in 
batch mode, inside a home-made script). For phonopy, all atoms must be 
inequivalent, for proper results. Since I run FIRST all the 
initializations, and keep a log file, I am in position to tell if the 
spacegroup of all structures is P1, which again, is a primary target for 
a good phonopy calculation.

So, your suggestion to decrease the duration of the convergence for the 
n+1 cases is to

cp case_n/case_n.clmsum  case_n+1/case_n+1.clmsum for 1<n<=Number of 
displacements

after the initialization of the cases and the run of case_1.
Are there any other files that could be transfered, therefor, enhance 
this idea even more?



-- 
Ioannis Madesis (Μαδέσης Ιωάννης)
PhD Student
Atomic and Molecular Physics
Department of Physics
University of Crete
(0030)-210-6503598