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[Stefano Baroni]

Dear Wang Yanchao,

"phonon" applies calculates the response of the system to the  
displacement of individual ions. In case you have not already done  
so, you may find interesting to take a glance at the theory such as  
explained, e.g. in Rev. Mod. Phys. 73, 515 - 562 (2001).

Happy New Year - Stefano Baroni

On Jan 2, 2007, at 6:58 AM, wang yanchao wrote:

> dear users:
>     When I caculate the phonon of the k-point(not gamma),according  
> to linear response theory, it should be apply perturbations. But I  
> donot  know how to added it and where it to be added?
>  I have read the code which to caculate scf ,nscf and phonon, I  
> think perturbations should be added in nscf,because in code of scf 
> (nscf) there is a subroutine "move ion",but in nscf ,the "switch"  
> is "-1". but the condition to call subroutine of "move ion" is   
> that the value of "iswitch" is bigger "0".Now I am confused. If  
> someone know it ,please tell me .thank you in advance.
>

---
Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center -  
Trieste
[+39] 040 3787 406 (tel) -528 (fax) / stefanobaroni (skype)

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