On 05/06/2025 16:57, Paolo Giannozzi wrote:
I could reproduce your results with v.6.4.1, though
more exactly: I could reproduce, using the latest (development) version
of QE, the results you obtained with QE v.6.4.1. So it is not a
version-dependent problem, but a system-dependent one. By the way: with
a smaller cutoff and k-point grid, all three components of the
dielectric tensors become very large and the anomaly disappears as well!
Paolo
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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_______________________________________________________________________________
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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.
--------------------------------------------------------------------------------
Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
users mailing list [email protected]
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