[Wien] Phonon calculation

[Peter Blaha]

> 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

You can "override the symmetry detection: Just label atoms which would be equivalent as   Mg1, Mg2,....

PS: For a phonon calculation you should use a better criterium than   -fc 1, use more like -fc 0.1 or less.

> 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?
>
> Today, I came to the realization, that the idea worked! I am currently running a calculation with 78 displacements.
> At #15 and greater, I replaced the recommended file, with the one proposed. The results so far, are the following:
> The first 14 structures required required 20-21 cycles for -cc 0.001 -ec 0.001 -fc 1 convergence. So, at this point I regard them as the "rule" for the duration.
> Of following 15 structures that have run since the replacement, 11 required only 12 cycles, with the same convergence criteria. Checking the time of the last modification,
> I can see that the 12 cycles require 54 minutes, whereas the 20 cycles require 86. If one combines the "success rate" (so far) with the improvement in time for convergence
> (For the particular sample with 52 atoms), the result is 25% improvement, that could probably go up to 37%, depending on the following "success rate".
>

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Peter Blaha
Inst. Materials Chemistry, TU Vienna
Getreidemarkt 9, A-1060 Vienna, Austria
Tel: +43-1-5880115671
Fax: +43-1-5880115698
email: pblaha at theochem.tuwien.ac.at
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