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<div class="elementToProof" style="margin-top: 1em; margin-bottom: 1em; font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Dear Quantum ESPRESSO Team,</div>
<div class="elementToProof" style="margin-top: 1em; margin-bottom: 1em; font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
I am performing phonon and EPW calculations for monolayer MoS2 using Quantum ESPRESSO and EPW. After applying the acoustic sum rule (ASR), the phonon dispersion from
<code>matdyn.x</code> looks correct and physically consistent.</div>
<div class="elementToProof" style="margin-top: 1em; margin-bottom: 1em; font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
However, when comparing these results with the phonon frequencies interpolated in EPW, I observe a
<b>negative frequency near the Gamma point</b> that does not appear in the <code>
matdyn.x</code> results.</div>
<div class="elementToProof" style="margin-top: 1em; margin-bottom: 1em; font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Could you please advise what might cause this discrepancy and how I can improve the simulation to achieve better agreement between the two?</div>
<div class="elementToProof" style="margin-top: 1em; margin-bottom: 1em; font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Attached are my input files for the <code>ph.x</code>, <code>matdyn.x</code>, and
<code>epw.x</code> runs for reference.</div>
<div class="elementToProof" style="margin-top: 1em; margin-bottom: 1em; font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Thank you for your time and your support.</div>
<div class="elementToProof" style="margin-top: 1em; margin-bottom: 1em; font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Kind regards,</div>
<div class="elementToProof" style="margin-top: 1em; margin-bottom: 1em; font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Sally Issa</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<b><u>Q2r.in: </u></b></div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
&input</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
fildyn = '/scratch/MoS2/phonons/MoS2.dyn',</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
zasr = 'crystal',</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
flfrc = './MoS2.espresso.ifc2'</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
write_lr = .true.</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
loto_2d=.true.</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
/</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<b><u>Ph.in: </u></b></div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
&inputph</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
prefix = 'MoS2',</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
amass(1) = 95.95,</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
amass(2) = 32.065,</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
outdir = '/scratch/MoS2/phonons/ph661-input'</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
fildyn = '/scratch/MoS2/phonons/MoS2.dyn'</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
ldisp = .true.,</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
recover = .true.,</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
epsil = .true. </div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
fildvscf = 'dvscf',</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
nq1=6,</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
nq2=6,</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
nq3=1,</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
tr2_ph = 1.0d-13</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
/</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<b><u>Epw.in: </u></b></div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<b><u><br>
</u></b></div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
&inputepw</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
prefix = 'MoS2'</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
outdir = '/scratch/MoS2/epw/epw_dir_q661_k18181/'</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
amass(1) = 95.95 ! Mo</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
amass(2) = 32.065 ! S</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<br>
</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
elph = .true. </div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
kmaps = .false. </div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
epbwrite = .true. </div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
epbread = .false.</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<br>
</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
!ephwrite = .true. </div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
epwwrite = .true. </div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
epwread = .false. </div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<br>
</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
etf_mem = 1 </div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<br>
</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
! polar/2D long-range treatment </div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
lpolar = .true.</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
system_2d = .true. ! v5.3 accepts logical; (string choices arrive later)</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
asr_typ = 'crystal'</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<br>
</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
!band subspace / excluded bands for Wannierization</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
nbndsub = 11</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
bands_skipped = 'exclude_bands = 1:6' ! exclude first 6 bands from wannierization</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<br>
</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
! internal wannierization (uses libwannier90)</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
wannierize = .true.</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
num_iter = 1000</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
dis_win_min = -10</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
dis_win_max = 4</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
dis_froz_min= -10</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
dis_froz_max= 3</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
proj(1) = 'Mo:d'</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
proj(2) = 'S:p'</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<br>
</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
! pass-through to wannier90 via wdata</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
wdata(1) = 'bands_plot = .true.'</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
wdata(2) = 'begin kpoint_path'</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
wdata(3) = 'G 0.000 0.000 0.000 K 0.333333333 0.333333333 0.0000000'</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
wdata(4) = 'K 0.333333333 0.333333333 0.0000000 M 0.5 0.0 0.000000'</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
wdata(5) = 'M 0.5 0.0 0.000000 G 0.0 0.0 0.0'</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
wdata(6) = 'end kpoint_path'</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
wdata(7) = 'bands_plot_format = gnuplot'</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
wdata(8) = 'guiding_centres = .true.'</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
wdata(9) = 'kmesh_tol = 1.0e-6'</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
wdata(10) = 'search_shells = 40'</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<br>
</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
iverbosity = 0</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<br>
</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
!self-energies / Eliashberg off</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
elecselfen = .false.</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
phonselfen = .false.</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
a2f = .false.</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<br>
</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
!Fermi level control</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
efermi_read = .true.</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
fermi_energy= -1.7901 ! eV</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<br>
</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
!plotting along paths (EPW will read filkf/filqf when band_plot=.true.)</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
band_plot = .true.</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
dvscf_dir = '/scratch/MoS2/phonons/ph661-input/save'</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
filkf = './highsymkpts.txt' </div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
filqf = './highsymkpts.txt' </div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<br>
</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
nk1 = 18 </div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
nk2 = 18 </div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
nk3 = 1</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<br>
</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
nq1 = 6 </div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
nq2 = 6 </div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
nq3 = 1</div>
<div style="font-family: "Calibri", "Helvetica", sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
/</div>
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