[Pw_forum] About phonon dispersion

[Lorenzo Paulatto]

On Tue, 26 Jan 2010 08:57:48 +0100, Shyam Khambholja  
<physik.shyam at gmail.com> wrote:
>      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.

Dear Shyam,
those are not errors, the code is just telling you that you will not have  
LO-TO splitting because you have not specified the necessary parameters in  
the phonon input file (epsil=.true., or zue=.true., I think). Anyway, not  
all materials present a LO-TO splitting: you can just check the literature  
to verify if you have to worry in your specific case.

regards

-- 
Lorenzo Paulatto

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