[Pw_forum] Phonon calculations
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,
- 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
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
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
filmol character as above, in a format suitable for 'molden'
filxsf character as above, in axsf format suitable for xcrysden
Lorenzo Paulatto IdR @ IMPMC/CNRS & Université Paris 6
phone: +33 (0)1 44275 084 / skype: paulatz
mail: 23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05
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