[Pw_forum] phonon at q=0

[Stefano Baroni]

Dear Mayanka,

is this a polar material? If so, the violation of the ASR may be justified by the use of too coarse a k-point mesh. Please, provide more details on the system and the calculations you are doing. 

SB

On Jul 1, 2011, at 6:17 AM, mayank gupta wrote:

> Dear All
> I have a query ragrdin phonon calculations at q=0. When I performed
> the phonon caclualtion at q=0, we didn't get zero enrgy for acoustic
> branches, however they can be set to zero by using acoustic/ crystal
> sum rules. My question is if the zone center acoustic braches values
> are too large (4 THz) even we have implemented very high convergence,
> it is ok to apply ASR.
> 
> Thanks
> 
> -- 
> Mayank
> 
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---
Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center - Trieste
http://stefano.baroni.me [+39] 040 3787 406 (tel) -528 (fax) / stefanobaroni (skype)

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