[Pw_forum] Imaginary Frequency

[Paolo Giannozzi]

It is impossible to answer on the basis of so little
information. It is difficult even in presence of all
needed information, since complete phonon dispersions
take so long to complete. 

Reminder: under some circumstances, phonons in v.5.0.2
may turn out to be incorrect. Use patched version 5.0.3.

P.


On Mon, 2013-11-18 at 09:44 +0900, Myungchul Jung wrote:
> Hi users,
>  
> In ABO3 structure, I consider an Osomate system.
> I used a PBE-pseudopotential.
> ecut = 40 Ry, ecutrho=400 Ry.
> First I used k-mesh 14*14*14 and q-mesh 2*2*2, then I got the
> imaginary freq.
> So, I used k-mesh 20*20*20 and q-mesh 2*2*2, then I didn't get the
> freq.
> But, when I used 4*4*4 q-mesh, I got a imaginary freq again.
> How I do to solve this problem?
>  
> Sincerely,
> Myung-Chul.
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-- 
Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222