[Pw_forum] Phonon negative Frequency

[Thomas Brumme]

Dear Suresh,

unfortunately, there is no way to know this before - or at least I don't 
know of any.
Yet, you'll nearly always have 3 negative frequencies at the Gamma point 
which should actually be zero. Furthermore, it is really important that 
you relax your system really carefully before attempting a phonon 
calculation - in fact, you should also decrease the convergence 
threshold for the scf from the standard 1.D-6 to maybe 1.D-8.

Kind regards

Thomas


On 29.11.2017 06:24, Suresh A wrote:
> Dear All,
>              I am ran phonon calculation for anatase previously and 
> got negative frequencies. I was install QE-5.2.0 in serial mode and 
> took days to finish the calculation in my desktop.
>
> Is there any way to know the negative frequency before the calculation 
> ends? So that the time can be saved.
>                                  Thank You
>
> Yours Sincerly,
>
> A.Suresh,
> Research Scholar,
> School of Physics,
> Madurai Kamaraj University,
> Madurai.
>
>
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-- 
Dr. rer. nat. Thomas Brumme
Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry
Leipzig University
Phillipp-Rosenthal-Strasse 31
04103 Leipzig

Tel:  +49 (0)341 97 36456

email: thomas.brumme at uni-leipzig.de

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