Apologies all in the q2r and matdyn files zasr and asr should both be 'simple' and NOT 'crystal'
________________________________ From: pw_forum-boun...@pwscf.org <pw_forum-boun...@pwscf.org> on behalf of Abualnaja, Faris <f.abualnaj...@imperial.ac.uk> Sent: 21 April 2016 16:42 To: pw_forum@pwscf.org Subject: [Pw_forum] Graphene Phonons Not Working To whom it may concern, I've been having trouble lately trying to produce graphene phonon dispersion plots. I am currently using quantum-espresso/5.0.2. I ran an scf calculation using an LDA norm conserving pseudo potential (C.pz-vbc.UPF). I found an optimised lattice parameter of 4.698 (Bohr) using a vc-relax calculation. I then ran an scf with the optimised lattice parameter and ecutwfc. I then proceeded onto producing a band structure with the following k-points in units of 2pi/a (Gamma (0,0,0) - K (0.33333, 0.57735027, 0) - M (0.5, 0.28867513, 0)). The band structure agrees with literature, where the dirac points meet at the K point. I then moved on to calculating the phonon at each k (or q) point. I ran the scf calculation once again in a new directory, I ran the phonon at gamma, K, and M. the results seemed to agree with literature. However, when I ran the phonon dispersion calculation, the results go all over the place. The gamma k and m points are the same but the curve is not expected. Obviously, after running the ph.x I ran a q2r.x calculation, followed by a matdyn.x calculation. To be clear I checked my k-points, I checked the k-path, the mp grid I used was 12x12x1 when calculating the phonon dispersion and 48x48x1 when running an scf calculation. Also, to clarify I did the tutorial for Al and Si and produced correct plots. Below are my input files: ------------------------------------------------------------------------------------------------------------------------------------ -------- SCF --------------------------------------------------------------------------------------------------------------------- &CONTROL prefix = 'graphene' pseudo_dir = '/home/fa2215/bin/upf_files' calculation = 'scf' restart_mode = 'from_scratch' verbosity = 'high' tprnfor = .TRUE. tstress = .TRUE. etot_conv_thr = 1.0D-4 forc_conv_thr = 1.0D-3 nstep = 50000 wf_collect = .TRUE. / &SYSTEM ibrav = 4 celldm(1) = 4.698 celldm(3) = 18.616 nat = 2 ntyp = 1 nbnd = 10 ecutwfc = 110 ecutrho = 440 occupations = 'smearing' smearing = 'mp' degauss = 0.1 / &ELECTRONS diagonalization = 'david' electron_maxstep = 1000 conv_thr = 1.0e-8 mixing_beta = 0.3 / ATOMIC_SPECIES C 12.01 C.pz-vbc.UPF ATOMIC_POSITIONS crystal C 0.6666666666 0.3333333333 0.0000000000 C 0.3333333333 0.6666666666 0.0000000000 K_POINTS (automatic) 48 48 1 0 0 0 ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ ------ PHONON --------------------------------------------------------------------------------------------------------------------- Phonon Dispersion of graphene &inputph tr2_ph=1.0d-12 ldisp=.true. nq1=12 nq2=12 nq3=1 prefix='graphene' amass(1)=12.01 outdir='/work/fa2215/Computational_Data/Graphene/Flat_Graphene/NM_PZ_LDA/Phonon_Calc/Disp/Disp2' fildyn='graphene.dyn' / ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ ----------- Q2R -------------------------------------------------------------------------------------------------------------------- &input fildyn='graphene.dyn', zasr='crystal', flfrc='graphene.fc' / ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ -------- MATDYN ------------------------------------------------------------------------------------------------------------------- &input asr='crystal' amass(1)=12.01 flfrc='graphene.fc' flfrq='graphene.freq' / 219 0.000000 0.000000 0.000000 1.0 : : : : ------------------------------------------------------------------------------------------------------------------------------------ So to recap my procedure was as follows: scf phonon disp q2r matdyn Let me know if anything is unclear and thank you for your help! Best, Faris
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