[Pw_forum] About phonon dispersion

[Eyvaz Isaev]

Dear Shyam,

Nothing is wrong with your calculations.
The message just states you have metallic system (find a line with "F"  in your IFC file), but not semiconducting. "F" (FALSE) means your IFC file does  not contain neither macroscopic dielectric constant, nor Born effective charges (hence, LO-TO splitting) which  are relevant for semiconducting(insulating) system. Please have a look at a textbok, why?

Bests,
Eyvaz.
 
-------------------------------------------------------------------
Prof. Eyvaz Isaev, 
Theoretical Physics Department, Moscow State Institute of Steel & Alloys, Russia, 
Department of Physics, Chemistry, and Biology (IFM), Linkoping University, Sweden 
Condensed Matter Theory Group, Uppsala University, Sweden 
Eyvaz.Isaev at fysik.uu.se, isaev at ifm.liu.se, eyvaz_isaev at yahoo.com


--- On Tue, 1/26/10, Shyam Khambholja <physik.shyam at gmail.com> wrote:

> From: Shyam Khambholja <physik.shyam at gmail.com>
> Subject: [Pw_forum] About phonon dispersion
> To: pw_forum at pwscf.org
> Date: Tuesday, January 26, 2010, 10:57 AM
> Dear all,
>             I want to compute phonon
> dispersion curves for nickel. when running q2r.in file,
>             I am getting following
> message.
>  
>            reading grid info from file
> ni.dyn0
>            reading force constants from file
> ni.dyn1
>            Dielectric tensor not
> found.
>            nqs=1
>           q = 0.00 0.00 0.00
>           
>  
>  please tell me the error in ni.ph.in
> file.
>  
>   Here is the ni.ph.in file
> #################################################
> 
> &inputph
>  
> tr2_ph=1.0d-14,
>  
> prefix='ni',
>  
> ldisp=.true.,
>  
> nq1=4,
>  
> nq2=4,
>  
> nq3=4,
>  
> amass(1)=58.71,
>  
> outdir='/home/birju/tmp/',
>  
> fildyn='ni.dyn',
>  /
> ###########################################
>       Also, when I am running matdyn.x
> program, I am getting following message.
>  
> 
>     
> from matdyn : info #       
> -1
>      Z* not found in file
> ni444.fc, TO-LO splitting at q=0 will be absent!
> 
>      A direction for q was not
> specified:TO-LO splitting will be absent
>      from matdyn : info #        -1
> 
>      Z* not found in file
> ni444.fc, TO-LO splitting at q=0 will be absent!
>      A direction for q was not
> specified:TO-LO splitting will be absent
> 
>            
> So,
> please help me. 
> Thanks
> in advance.
> -- 
> Shyam G Khambholja
> Reseach student,
> Depratment of Physics,
> Sardar Patel University 
> 
> -----Inline Attachment Follows-----
> 
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