[Pw_forum] phonon modes identification

Paolo Giannozzi giannozz at nest.sns.it
Thu Dec 16 10:40:05 CET 2004

On Monday 13 December 2004 04:50, W. YU wrote:

> the eigenvectors given in the Dyn files are complex
> numbers.

they are complex for a generic q. At q=0 only the real part 
should be present, but the diagonalization routine might 
add an overall phase, so beware. Program "dynmat" reads
the dynamical matrix at q=0, adds the long-range terms,
writes down the atomic displacements in a format that
is suitable for visualization with "molden". It is a very
simple code that can be easily adapted to write other
output formats

> Plus, the eigenvectors are given in cartesian 
> coordinates, I hope to know how is this coordinate
> system chosen?

you mean: "how are crystal axis oriented with respect
to cartesian axis" ? it is explained at the end of file 


Paolo Giannozzi             e-mail:  giannozz at nest.sns.it
Scuola Normale Superiore    Phone:   +39/050-509876, Fax:-563513 
Piazza dei Cavalieri 7      I-56126 Pisa, Italy

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