[Pw_forum] Format of Dynamical Matrix

Mohsen Modaresi modaresi.mohsen at gmail.com
Tue Jun 18 10:08:08 CEST 2013

Dear Developers,

I am trying to understand the structure of ***.dyn** files (ph.x out puts).
I face with 3 questions and can not find any proper answers from the *.f90
files and previous discussions,

1) The Dynamical Matrix is calculated for two q points in each ***.dyn**
files. But the Diagolnalization is done for only the first q point. I
search in the *.f90 files and find the algorithm to calculate the q (star).
I can not understand what is the necessity of the second q point?

2) I expect a (3Nat*3Nat) for dynamical matrix so the eigen vectro which
are written in the end of file should be a (1*3*Nat) matrix but instead i
see a (3*3) matrix, for example (Real+Imaginary),
  omega( 1) =       7.786434 [THz] =     259.729218 [cm-1]
 (  1.000000  0.000000  0.000087  0.000000 -0.000130  0.000000 )
 (  0.000344  0.000000  0.000028  0.000000 -0.000144  0.000000 )
 ( -0.000346  0.000000  0.000095  0.000000 -0.000016  0.000000 )

3) I also worked with Vibra in the Siesta package. In this code the
positive and negative displacement for atoms in each direction is
considered but i can not find the same procedure in the ph.x.
Could you please give a proper answer and provide a description of the out
put files of ph.x?

Best Regards,

Mohsen Modarresi,
PhD student of Solid State Physics,
 Ferdowsi University of Mashhad, Iran.
Phone +98-913-345-2131
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