[Pw_forum] phonon dispersion jagged

[Ante Bilic]

Hello,

I've tried to calculate the phonon spectrum of a cubic perovskite
using PWSCF. All the input files (and *.freq output)  are in the
attached archive. Basically, I followed the AlAs example06 that is
provided with the distribution. At first I used the 4x4x4 grid to evaluate
the density matrices. The calculated dispersion curves were in
very good agreement with those in the literature, except they look
shockingly ugly! For some reason they are not smooth, but rather
jagged. I thought a denser mesh might fix that so I tried 6x6x6, and
then 8x8x8 but the curves looked just as ugly (if not uglier).

I believe the SCF calculation for the bulk was of a good quality, with ecut=36.4 Ry,
and ecutrho=300 Ry, k-point grid was 6x6x6, and all the convergency
requirements were rather strict, for both SCF and phonon calculations.

Could you please have a look into the provided files, perhaps you can spot
some inappropriate settings etc.

Thanks in anticipation,
-Ante

This email is confidential and may be privileged. If you are not the intended recipient, please delete it and notify us immediately. Please do not copy or use it for any purpose, or disclose its contents to any other person. Thank you.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: pervk.tar.gz
Type: application/x-gzip
Size: 8105 bytes
Desc: pervk.tar.gz
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20081028/ebedd19b/attachment.bin>