[Pw_forum] Doubt in Phonon calculations

[Stefano Baroni]

All the modes are cakculated. Degenerate modes are calculated because  
all of the partners of irreps are needed to properly symmtetrize the  
dynamical matrix (or else, one should use more k-points than actually  
used in ph.x). Acoustic modes are calculated for the sake of it  
(actually, the amount of violation of the acoustic sum rule tells  
something about the overall convergence of the calculation).  Stefano  
Baroni - Trieste

---
swift text written and sent on the go

On 11/ago/2009, at 14.48, Bipul Rakshit <bipulrr at gmail.com> wrote:

> Dear PWSCF users,
> I am doing phonon of LaMnO3, which is having 20 atoms in the unit  
> cell (After finishing the electronic part)
> I am just calculating the phonon at Gamma point for this compound. I  
> have send the relevant input files also.
> My doubt is if you see the O/P of phonon (phonon.out) file, it seems  
> it is going to calculate all the 60 modes.
> But as far as I know at gamma atleast few modes are degenerate and  
> acoustic is zero.
>
> So kindly look at the input files and tell the possible error
> regards
> -- 
> Dr. Bipul Rakshit
> Research Associate,
> S N Bose Centre for Basic Sciences,
> Salt Lake,
> Kolkata 700 098
> India
> <lamno3.ph.in>
> <lamno3.scf.in>
> <lamno3.scf.out>
> <phonon.out>
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