Try reducing the tr2_ph parameter. 1D-11 is too high. I have had similar problems in the past and it was solved by reducing tr2_ph. I would suggest trying 1D-13 or 1D-14. -Sridhar Purdue University
On Mon, Oct 19, 2015 at 9:36 PM, 潭影空人心 <774729...@qq.com> wrote: > Dear all, > I used nq1 = 2, nq2 = 2, nq3 = 2 and nq1 = 4, nq2 = 4, nq3 = 4 > ,respectively, to do a phonon calculation. There is no imaginary > frequency at the calculated Q points, but after calculations of Q2R and > MATDYN, imaginary frequencies appear near GAMMA point(not GAMMA point). > > My settings are as follows: > 1.lattice relaxation under pressure: > &control > calculation = 'vc-relax' > > restart_mode = 'from_scratch' > prefix = 'cras' > > pseudo_dir = '/data1/tan1/software/espresso-5.1/pseudo/' > outdir = './tempdir/' > etot_conv_thr = 1.0D-6 > forc_conv_thr = 1.0D-4 > tstress = .true. > tprnfor = .true. > > / > &system > ibrav = 8 > A = 5.58 > B = 3.36 > C = 6.17 > nat = 8 > ntyp = 4 > ecutwfc = 120 > occupations = 'smearing' > smearing = 'methfessel-paxton' > degauss = 0.04 > nspin = 2 > starting_magnetization(1) = -1 > starting_magnetization(2) = 1 > starting_magnetization(3) = 0 > starting_magnetization(4) = 0 > / > &electrons > electron_maxstep = 100 > conv_thr = 1.0d-6 > mixing_beta = 0.7 > > / > &ions > ion_dynamics = 'bfgs' > / > &cell > press = 1500 > cell_dynamics = 'bfgs' > press_conv_thr = 0.1 > cell_factor = 2.5d0 > / > ATOMIC_SPECIES > Cr1 51.9961 Cr.pz-hgh.UPF > Cr2 51.9961 Cr.pz-hgh.UPF > As1 74.9216 As.pz-hgh.UPF > As2 74.9216 As.pz-hgh.UPF > ATOMIC_POSITIONS (crystal) > Cr1 0.012000 0.250000 0.201000 1 0 1 > Cr2 0.988000 0.750000 0.799000 1 0 1 > Cr2 0.512000 0.250000 0.299000 1 0 1 > Cr1 0.488000 0.750000 0.701000 1 0 1 > As1 0.195000 0.250000 0.582000 1 0 1 > As2 0.805000 0.750000 0.418000 1 0 1 > As2 0.695000 0.250000 0.918000 1 0 1 > As1 0.305000 0.750000 0.082000 1 0 1 > K_POINTS {automatic} > > 6 8 6 0 0 0 > > > 2.interior coordination relaxation: > All is the same as above, but "ecutwfc = 50" > 3.self-consistent iteration for phonon calculation: > &control calculation = 'scf' restart_mode = 'from_scratch' prefix = 'cras' > pseudo_dir = '/data1/tan1/software/espresso-5.1/pseudo/' outdir = > './tempdir/' tstress = .true. tprnfor = .true. / &system ibrav = 0 > celldm(1) = 10.54467182 nat = 8 ntyp = 4 ecutwfc = 50 occupations = > 'smearing' smearing = 'methfessel-paxton' degauss = 0.05 nspin = 2 > starting_magnetization(1) = -1 starting_magnetization(2) = 1 > starting_magnetization(3) = 0 starting_magnetization(4) = 0 / &electrons > electron_maxstep = 200 conv_thr = 1.0d-10 mixing_beta = 0.7 / > ATOMIC_SPECIES Cr1 51.9961 Cr.pz-hgh.UPF Cr2 51.9961 Cr.pz-hgh.UPF As1 > 74.9216 As.pz-hgh.UPF As2 74.9216 As.pz-hgh.UPF CELL_PARAMETERS (alat= > 10.54467182) 0.9146 0.0000 0.0000 0.0000 0.4765 0.0000 0.0000 0.0000 0.9628 > ATOMIC_POSITIONS (crystal) Cr1 0.0104 0.2500 0.1827 Cr2 0.9896 0.7500 > 0.8173 Cr2 0.5104 0.2500 0.3173 Cr1 0.4896 0.7500 0.6827 As1 0.1833 0.2500 > 0.5616 As2 0.8167 0.7500 0.4384 As2 0.6833 0.2500 0.9384 As1 0.3167 0.7500 > 0.0616 K_POINTS {automatic} 6 8 6 0 0 0 > 4.self-consistent iteration for electron-phonon coupling: > All is the same as phonon calculation but k-mesh 12 16 12,and in addition > to "la2F = .true.". > 5.phonon calculation: > &inputph tr2_ph = 1.0d-11 prefix = 'cras' fildvscf = 'crasdv' amass(1) = > 51.9961 amass(2) = 51.9961 amass(3) = 74.9216 amass(4) = 74.9216 outdir = > './tempdir/', fildyn = 'cras.dyn', electron_phonon='interpolated' > el_ph_sigma = 0.005, el_ph_nsigma = 10, trans = .true. ldisp = .true. > alpha_mix(1) = 0.5 recover =.true. nq1 = 2 nq2 = 2 nq3 = 2 / > 6.q2r: > &input zasr='crystal', fildyn='cras.dyn', flfrc='cras222.fc', la2F=.true. / > 7.&input asr='crystal', > amass(1)=51.9961,amass(2)=51.9961,amass(3)=74.9216,amass(4)=74.9216, > flfrc='cras222.fc', flfrq='cras.freq', q_in_band_form=.true., > la2F=.true.,dos=.false. / 8 0.000000 0.000000 0.000000 50 0.500000 0.000000 > 0.000000 50 0.500000 0.785906 0.000000 50 0.000000 0.000000 0.000000 50 > 0.000000 0.000000 0.456275 50 0.500000 0.000000 0.456275 50 0.500000 > 0.785906 0.456275 50 0.000000 0.000000 0.456275 1 > > I am eagerly hoping someone can help me. > > Thank you. > > > tanlin > > 2015.10.20 > > > _______________________________________________ > Pw_forum mailing list > Pw_forum@pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum >
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