<div dir="ltr"><div>Hi QE users</div><div><br></div><div>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.</div><div><br></div><div>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.</div><div><br></div><div>Could anyone help me understand the origin of these two issues:<br>1) in the top figure, v.6.4.1 the anomalous U-shape of one of the acoustic branches near the gamma point.</div><div>2) In v. 7.3, the oscillations around the gamma and A points.</div><div><br></div><div>Any insights or suggestions would be appreciated</div><div><br></div><div>Here are the <a href="http://ph.in">ph.in</a>, <a href="http://q2r.in">q2r.in</a>, <a href="http://matdyn.in">matdyn.in</a></div><div><br></div><div>Phonons of InN at G!=0<br>&inputph<br> tr2_ph = 1.0d-14,<br> ldisp = .true.,<br> search_sym = .false.,<br> prefix = 'inn-ph',<br> recover = .true.<br> fildyn = 'inn-ph.dyn',<br> nq1 = 5,<br> nq2 = 5,<br> nq3 = 3,<br> amass(1) = 114.818,<br> amass(2) = 14.007,<br> outdir = './tmp'<br> /</div><div><br></div><div>&INPUT<br> fildyn = 'inn-ph.dyn',<br> zasr = 'crystal'<br> flfrc = 'inn-ph.fc'<br> /<br></div><div><br></div><div>&input<br> asr = 'crystal',<br> flfrc = 'inn-ph.fc',<br> flfrq = 'inn.band.freq'<br> flvec = 'inn.band.modes'<br> amass(1) = 114.818,<br> amass(2) = 14.007,<br> q_in_band_form = .true.<br> /<br>8<br> 0.0000000000 0.0000000000 0.0000000000 40 ! Gamma<br> 0.5000000000 0.0000000000 0.0000000000 25 ! M<br> 0.3333333333 0.3333333333 0.0000000000 40 ! K<br> 0.0000000000 0.0000000000 0.0000000000 25 ! Gamma<br> 0.0000000000 0.0000000000 0.5000000000 40 ! A<br> 0.5000000000 0.0000000000 0.5000000000 25 ! L<br> 0.3333333333 0.3333333333 0.5000000000 40 ! H<br> 0.0000000000 0.0000000000 0.5000000000 1 ! A</div><div><br></div><div>Regards,</div><div><br></div><span class="gmail_signature_prefix">-- </span><br><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div dir="ltr"><div><div><p class="MsoNormal" style="background-image:initial;background-position:initial;background-repeat:initial"><span style="font-family:Arial,sans-serif">Iván Darío Arellano Ramírez</span></p>
<p class="MsoNormal" style="background-image:initial;background-position:initial;background-repeat:initial"><span style="font-family:Arial,sans-serif">Profesor Titular Programa de Ingeniería Física</span></p>
<p class="MsoNormal" style="background-image:initial;background-position:initial;background-repeat:initial"><span style="font-family:Arial,sans-serif">Director Grupo de Investigación en Modelado y Simulación Computacional</span></p>
<p class="MsoNormal" style="text-align:justify"><span style="font-family:Arial,sans-serif;background-image:initial;background-position:initial;background-repeat:initial">Universidad
Tecnológica de Pereira</span><span lang="RU"></span></p></div></div></div></div></div></div>
<br>
<span style="font-family:arial,sans-serif;font-size:12.8px;text-align:justify;background-color:rgb(255,255,255)">El contenido de este mensaje y sus anexos son únicamente para el uso del destinatario y pueden contener información clasificada o reservada. Si usted no es el destinatario intencional, absténgase de cualquier uso, difusión, distribución o copia de esta comunicación.</span>