[Pw_forum] Phonon calculations

Lorenzo Paulatto Lorenzo.Paulatto at impmc.upmc.fr
Tue Nov 22 14:46:13 CET 2011

On Tue, 22 Nov 2011 14:39:30 +0100, henry odhiambo <henod2001 at yahoo.com>  

> Hello everyone,
>  I am doing phonon calculaions at the gamma point.
>  The issue is: how do I use the auxilliary code dynmat.x with the input   
> .dynG to obtain the ouptput dynmat.axsf? Is the command something like  
> dynmat.x <si.dynG> dynmat.axsf ? (which I suspect is wrong). Please,  
> help.

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 (default: q=(0,0,0) )
amass(nt) real    mass for atom type nt, a.u.
                   (default: amass is read from file fildyn)
asr   character   indicates the type of Acoustic Sum Rule imposed
                    - 'no': no Acoustic Sum Rules imposed (default)
                    - 'simple':  previous implementation of the asr used
                    (3 translational asr imposed by correction of
                    the diagonal elements of the dynamical matrix)
                    - 'crystal': 3 translational asr imposed by optimized
                    correction of the dyn. matrix (projection).
                    - 'one-dim': 3 translational asr + 1 rotational asr
                    imposed by optimized correction of the dyn. mat. (the
                    rotation axis is the direction of periodicity; it
                    will work only if this axis considered is one of
                    the cartesian axis).
                    - 'zero-dim': 3 translational asr + 3 rotational asr
                    imposed by optimized correction of the dyn. mat.
                    Note that in certain cases, not all the rotational asr
                    can be applied (e.g. if there are only 2 atoms in a
                    molecule or if all the atoms are aligned, etc.).
                    In these cases the supplementary asr are cancelled
                    during the orthonormalization procedure (see below).
                    Finally, in all cases except 'no' a simple correction
                    on the effective charges is performed (same as in the
                    previous implementation).
axis    integer    indicates the rotation axis for a 1D system
                    (1=Ox, 2=Oy, 3=Oz ; default =3)
filout  character output file containing frequencies and modes
                   (default: filout='dynmat.out')
filmol  character as above, in a format suitable for 'molden'
                   (default: filmol='dynmat.mold')
filxsf  character as above, in axsf format suitable for xcrysden
                   (default: filmol='dynmat.axsf')

Lorenzo Paulatto IdR @ IMPMC/CNRS & Université Paris 6
phone: +33 (0)1 44275 084 / skype: paulatz
www:   http://www-int.impmc.upmc.fr/~paulatto/
mail:  23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05

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