[Pw_forum] ​propagation direction of LO-TO splitting for dynmat.in file phonon calculation

[stefano de gironcoli]

Dear Wei Li,

   from the header of the dynmat.f90 source code
!
!  This program
!  - reads a dynamical matrix file produced by the phonon code
!  - adds the nonanalytical part (if Z* and epsilon are read from file),
!    applies the chosen Acoustic Sum Rule (if q=0)
!  - diagonalise the dynamical matrix
!  - calculates IR and Raman cross sections (if Z* and Raman tensors
!    are read from file, respectively)
!  - writes the results to files, both for inspection and for plotting
!
!  Input data (namelist "input")
!
!  fildyn  character input file containing the dynamical matrix
!                    (default: fildyn='matdyn')
!  q(3)      real    calculate LO modes (add nonanalytic terms) along
!                    the direction q (cartesian axis, default: q=(0,0,0) )

the value of the vector q (when different from zero) is interpreted as 
the direction of propagation of the phonons.

stefano

On 25/12/2016 02:20, Wei Li wrote:
> ​​
> ​Hi Friends,
>
> I plan to calculate the infrared spectrum of anatase TiO2 bulk using 
> pw.x (scf), ph.x calculates phonon frequencies and effective charge 
> etc..  Then the dynmat.x is used to calculate LO-TO splitting.
>
> The ph.x calculation is performed at single q, i.e., q=0.0,0.0,0.0 in 
> ph.in <http://ph.in> file
>
> ​
> The question is how to define the
> ​​
> propagation direction of LO-TO splitting, q(i), i=1,2,3, in the 
> dynmat.in <http://dynmat.in> file?
>
> For instance, how to set q(1),q(2),q(3)?​
>
>
>
>
>
>
> -- 
> *Wei Li*
> PhD student
> State Key Lab of Theoretical & Computational Chemistry
> Institute of Theoretical Chemistry
> Jilin University
> Changchun, 130023
> P.R. China
> Email: liwei0099 at gmail.com <mailto:liwei0099 at gmail.com>
>
>
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