[Pw_forum] Questions on phonon calculation in Example02 and 06

[vtmtrinh at caltech.edu]

Thank you very much, Paolo.

I see what you said.  I'll verify the second part.  If I see anything
differnt, I'll let you know.

MyTrinh

>
> On Oct 15, 2009, at 2:16 , vtmtrinh at caltech.edu wrote:
>
>> I compared the 2 results from the 2 methods, I saw that both ways gave
>> the same phonon frequencies, but the displacement vectors are totally
>> different.
>
> no they aren't. Displacement vectors for non-degenerate modes (number 3
> and 6) are the same (within numerical accuracy). For degenerate
> modes, you
> get different linear combinations (because of the way matrix
> diagonalization
> works), but the subspace spanned by the two sets of degenerate
> eigenvectors
> is the same (I haven't verified, but I am sure it is: plase verify)
>
> P.
> ---
> Paolo Giannozzi, Dept of Physics, University of Udine
> via delle Scienze 208, 33100 Udine, Italy
> Phone +39-0432-558216, fax +39-0432-558222
>
>
>
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