<div dir="ltr"><div><br></div>Dear Vahid, <div><br></div><div>Thank you for your help, </div><div>changing <i>q_in_band_form=.true</i> to <i>q_in_cryst_coord</i>=.true resolves the problem as you suggested, </div><div><br></div><div>Cheers</div><div>Roozbeh</div><div>PDF, Physics, Queen's university</div><div><br></div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sat, Jan 23, 2021 at 12:56 AM Roozbeh Anvari <<a href="mailto:roozbeh.anvari@gmail.com">roozbeh.anvari@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><br><div><br>Dear Quantum Espresso experts, <br><br>I am having a trouble calculating the phonon bands of graphene at $K$-point, </div><div><br></div><div>I am using NC+LDA and NC+PBE, ecutwfs=60, Ecutrho=400.0, forc_conv_thr=1.0d-6, <br><br>as you can see in the attached figure, the calculated acoustic and optical eigenvalues are ok at $\Gamma$ and $M$-points, however the calculated value deviates from what it should be at $K$-point:<br>TA and ZA branches are not overlapping at $K$-point, </div><div>and a strange bump can be seen when ZO approaches $K$-point, <br><br>I have checked the convergence for K-mesh, Ecutwfs, and Ecutrho, <br>I have also tried increasing the K and q mesh for scf-calculation,<br>using tr2_ph = 1E-14 and alpha_mix(niter)= .1 also does not improve the results,<br><br><br>Thank you for your help, </div><div>Regards, <br>Roozbeh <br>PDF, physics, Queen's university </div><div><br> <br>Here is the setup I am using, </div><div><br> step 1, pw.x <br> <br> &CONTROL</div><div> ....<br> calculation='scf'<br> forc_conv_thr=1.0d-6, <br> /<br> <br> &SYSTEM<br> ibrav=0, nat = 2, ntyp = 1, <br> ecutwfc = 60.0 , ecutrho = 400.0, ! 480<br> nosym=.true.,<br> occupations='smearing', smearing='cold', degauss=0.02<br> la2F = .true., <br> /<br><br></div><div> &ELECTRONS<br> startingwfc='random'<br> diagonalization='cg'<br> conv_thr = 1.0e-12<br> mixing_beta = 0.2<br> electron_maxstep=200<br> <br> <br> ATOMIC_SPECIES<br> C 12.011 C.pz-vbc.UPF<br> <br> CELL_PARAMETERS (angstrom) <br> 2.428479517 -0.000000605 0.000000000<br> -1.214240282 2.103124989 0.000000000<br> 0.000000000 0.000000000 20.000000000<br> <br> ATOMIC_POSITIONS (crystal)<br> C -0.0002315717 0.0002344099 0.4996978700<br> C 0.6664267343 0.3335704066 0.4996978902<br> <br> K_POINTS automatic<br> 64 64 1 0 0 0 <br> <br> %--------------------<br> % step 2 ,pw.x <br> %--------------------<br> </div><div> same as above except<br> la2F = .false.,<br> K_POINTS automatic<br> 32 32 1 0 0 0<br> <br> %--------------------<br> % step 3 , ph.x <br> %--------------------<br> <br> <br> &inputph<br> tr2_ph=1.0d-14, <br> prefix='ml_gr',<br> fildvscf='ml_gredv',<br> amass(1)=12.011,<br> outdir='./tmp',<br> fildyn='ml_gr.dyn',<br> electron_phonon='interpolated',<br> !el_ph_sigma=0.005, <br> !el_ph_nsigma=10,<br> alpha_mix=0.1 <br> diagonalization='cg', <br> trans=.true.,<br> ldisp=.true.,<br> nq1=4 , nq2=4, nq3=1 <br> ! nq1=8 , nq2=8, nq3=1 makes no difference <br> /<br> <br> <br> %--------------------<br> % step 4 , q2r.x<br> %--------------------<br> <br> &input<br> zasr='simple',<br> fildyn='ml_gr.dyn', <br> flfrc='gr333.fc', <br> la2F=.true.<br> /<br> <br> <br> %--------------------<br> % step 5 , matdyn.x<br> %--------------------<br> <br> &input<br> asr='simple', <br> amass(1)=12.011,<br> flfrc='gr333.fc', <br> flfrq='gr333.freq', <br> la2F=.true.,<br> dos=.false.<br> q_in_band_form=.true.<br></div> /<br> 4<br> 0 0 0 20<br> 0 .5 0 20<br> -0.3333333 0.6666666 0. 20<br> 0 0 0 1<br></div>
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