[Pw_forum] Irreps and vibrational modes

[Elie M]

Thanks for the information, Prof. Giannozzi.
Elie

> Subject: Re: [Pw_forum] Irreps and vibrational modes
> From: giannozz at democritos.it
> To: elie.moujaes at hotmail.co.uk
> CC: pw_forum at pwscf.org
> Date: Mon, 14 May 2012 17:35:26 +0200
> 
> On Mon, 2012-05-14 at 03:07 +0100, Elie M wrote:
> 
> > (1) Are all the modes vibrational?
> 
> there are always three translational modes
> 
> > (2) Are any modes missing from the calculation
> 
> there shouldn't be anything missing
> 
> > (3) i did the calculation and got two of the modes negative
> 
> if they go to zero when you apply the acoustic sum rule, with all
> other modes unchanged or litle affected, it is not a problem
> 
> P.
> 
> -- 
> Paolo Giannozzi, IOM-Democritos and University of Udine, Italy
> 
> 
 		 	   		  
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