For EPW calculations, I generally use the lifc tag (see EPW documentation) which utilizes the force constants generated by the q2r.x. The EPW phonon dispersion then will match that of matdyn.x.
Best, Vahid Vahid Askarpour Department of Physics and Atmospheric Science Dalhousie University Halifax, Canada On Nov 5, 2025, at 4:25 AM, sally issa <[email protected]> wrote: CAUTION: The Sender of this email is not from within Dalhousie. Dear Quantum ESPRESSO Team, 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 matdyn.x looks correct and physically consistent. However, when comparing these results with the phonon frequencies interpolated in EPW, I observe a negative frequency near the Gamma point that does not appear in the matdyn.x results. Could you please advise what might cause this discrepancy and how I can improve the simulation to achieve better agreement between the two? Attached are my input files for the ph.x, matdyn.x, and epw.x runs for reference. Thank you for your time and your support. Kind regards, Sally Issa Q2r.in: &input fildyn = '/scratch/MoS2/phonons/MoS2.dyn', zasr = 'crystal', flfrc = './MoS2.espresso.ifc2' write_lr = .true. loto_2d=.true. / Ph.in: &inputph prefix = 'MoS2', amass(1) = 95.95, amass(2) = 32.065, outdir = '/scratch/MoS2/phonons/ph661-input' fildyn = '/scratch/MoS2/phonons/MoS2.dyn' ldisp = .true., recover = .true., epsil = .true. fildvscf = 'dvscf', nq1=6, nq2=6, nq3=1, tr2_ph = 1.0d-13 / Epw.in: &inputepw prefix = 'MoS2' outdir = '/scratch/MoS2/epw/epw_dir_q661_k18181/' amass(1) = 95.95 ! Mo amass(2) = 32.065 ! S elph = .true. kmaps = .false. epbwrite = .true. epbread = .false. !ephwrite = .true. epwwrite = .true. epwread = .false. etf_mem = 1 ! polar/2D long-range treatment lpolar = .true. system_2d = .true. ! v5.3 accepts logical; (string choices arrive later) asr_typ = 'crystal' !band subspace / excluded bands for Wannierization nbndsub = 11 bands_skipped = 'exclude_bands = 1:6' ! exclude first 6 bands from wannierization ! internal wannierization (uses libwannier90) wannierize = .true. num_iter = 1000 dis_win_min = -10 dis_win_max = 4 dis_froz_min= -10 dis_froz_max= 3 proj(1) = 'Mo:d' proj(2) = 'S:p' ! pass-through to wannier90 via wdata wdata(1) = 'bands_plot = .true.' wdata(2) = 'begin kpoint_path' wdata(3) = 'G 0.000 0.000 0.000 K 0.333333333 0.333333333 0.0000000' wdata(4) = 'K 0.333333333 0.333333333 0.0000000 M 0.5 0.0 0.000000' wdata(5) = 'M 0.5 0.0 0.000000 G 0.0 0.0 0.0' wdata(6) = 'end kpoint_path' wdata(7) = 'bands_plot_format = gnuplot' wdata(8) = 'guiding_centres = .true.' wdata(9) = 'kmesh_tol = 1.0e-6' wdata(10) = 'search_shells = 40' iverbosity = 0 !self-energies / Eliashberg off elecselfen = .false. phonselfen = .false. a2f = .false. !Fermi level control efermi_read = .true. fermi_energy= -1.7901 ! eV !plotting along paths (EPW will read filkf/filqf when band_plot=.true.) band_plot = .true. dvscf_dir = '/scratch/MoS2/phonons/ph661-input/save' filkf = './highsymkpts.txt' filqf = './highsymkpts.txt' nk1 = 18 nk2 = 18 nk3 = 1 nq1 = 6 nq2 = 6 nq3 = 1 / <matdyn.in><disp_qeandelphbolt.png><disp.pdf>_______________________________________________________________________________ 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<http://www.max-centre.eu/>) users mailing list [email protected]<mailto:[email protected]> https://lists.quantum-espresso.org/mailman/listinfo/users
_______________________________________________________________________________ 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] https://lists.quantum-espresso.org/mailman/listinfo/users
