Hi
I don't know the reasons for the weird behavior with v.7.3. If you have
split your calculation into partial one, that could be the reason
(sometimes the "splitting" machinery does not work as expected).
I could reproduce your results with v.6.4.1, though. If you look at the
output (or dynamical matrix file) for q=0, you will notice very large
values for the dielectric tensor along xx and yy. This indicates a
quasi-metallic character of your system, presumably as a consequence of
DFT shortcomings, spin-orbit interactions absence, or both. If you
replace in the dynamical matrix files the dielectric tensor with the
experimental one (exx = eyy = 14.4, ezz = 13.1) and re-compute the force
constant matrices, the anomalous behaviour at q => 0 disappears.
Thanks to Pietro Delugas and Lorenzo Paulatto for help on this subject.
Paolo
On 01/06/2025 01:07, Ivan Dario Arellano Ramirez wrote:
Hi QE users
Recently, I performed phonon calculations using the ph.x module
implemented in QE. I initially used the version 6.4.1 and obtained the
results shown in the attached figure (top). I noticed an
unusual behavior near the gamma point, one of the acoustic branches
exhibits a U-shaped anomaly with some negative frequencies (small
values). The acoustic modes should approach the Gamma point linearly.
After some time, I decided to repeat the calculations using identical
input file parameters, but on a different machine and with QE version
7.3. In this version, the band structures shows oscillations around both
the gamma and A points.
Could anyone help me understand the origin of these two issues:
1) in the top figure, v.6.4.1 the anomalous U-shape of one of the
acoustic branches near the gamma point.
2) In v. 7.3, the oscillations around the gamma and A points.
Any insights or suggestions would be appreciated
Here are the ph.in <http://ph.in>, q2r.in <http://q2r.in>, matdyn.in
<http://matdyn.in>
Phonons of InN at G!=0
&inputph
tr2_ph = 1.0d-14,
ldisp = .true.,
search_sym = .false.,
prefix = 'inn-ph',
recover = .true.
fildyn = 'inn-ph.dyn',
nq1 = 5,
nq2 = 5,
nq3 = 3,
amass(1) = 114.818,
amass(2) = 14.007,
outdir = './tmp'
/
&INPUT
fildyn = 'inn-ph.dyn',
zasr = 'crystal'
flfrc = 'inn-ph.fc'
/
&input
asr = 'crystal',
flfrc = 'inn-ph.fc',
flfrq = 'inn.band.freq'
flvec = 'inn.band.modes'
amass(1) = 114.818,
amass(2) = 14.007,
q_in_band_form = .true.
/
8
0.0000000000 0.0000000000 0.0000000000 40 ! Gamma
0.5000000000 0.0000000000 0.0000000000 25 ! M
0.3333333333 0.3333333333 0.0000000000 40 ! K
0.0000000000 0.0000000000 0.0000000000 25 ! Gamma
0.0000000000 0.0000000000 0.5000000000 40 ! A
0.5000000000 0.0000000000 0.5000000000 25 ! L
0.3333333333 0.3333333333 0.5000000000 40 ! H
0.0000000000 0.0000000000 0.5000000000 1 ! A
Regards,
--
Iván Darío Arellano Ramírez
Profesor Titular Programa de Ingeniería Física
Director Grupo de Investigación en Modelado y Simulación Computacional
Universidad Tecnológica de Pereira
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Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 206, 33100 Udine Italy, +39-0432-558216
_______________________________________________________________________________
The Quantum ESPRESSO Foundation stands in solidarity with all civilians
worldwide who are victims of terrorism, military aggression, and indiscriminate
warfare.
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