[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>
wrote:
> 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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