Dear QE users I am trying to calculate the phonon dispersion curves of PdS2 BILAYERS but it always give negative frequencies of the order of ~ -8 cm-1. Please have a look at my input file and feel free to edit it to make it more meaningful --------------------------------------------------------------------------------------------------------------- &control calculation = 'scf', restart_mode = 'from_scratch', pseudo_dir='~/pseudo_directory', outdir='./OUT', prefix='PtS2bs0', / &system ibrav = 4, a = 3.52, b = 3.52, c = 20.0, cosAB = -0.5, cosAC = 0.0, cosBC = 0.0, nat = 6, ntyp = 2, ecutwfc = 75, ecutrho = 300, nbnd = 40, occupations = 'smearing', smearing = 'gaussian', degauss = 0.001, / &electrons mixing_beta = 0.3, conv_thr = 1.0d-9, electron_maxstep = 900, / ATOMIC_SPECIES Pt 195.08 Pt.pbe-mt_fhi.UPF S 32.06 S.pbe-mt_fhi.UPF ATOMIC_POSITIONS angstrom Pt 0.00000000 0.00000000 0.00000000 S 1.80374872 1.02665089 1.24494264 S -1.80374872 -1.02665089 -1.24494264 Pt 0.00000000 0.00000000 6.70000000 S 1.80374872 1.02665089 7.94494264 S -1.80374872 -1.02665089 5.45505736 K_POINTS AUTOMATIC 16 16 4 0 0 0 ----------------------------------------------------------------------------- #phonon of unstrained structure &inputph prefix = 'PtS2bs0', tr2_ph = 1.0d-16, ldisp = .true., search_sym = .false., nq1 = 2, nq2 = 2, nq3 = 1, amass(1) = 195.08, amass(2) = 32.06, outdir = './OUT', fildyn = 'PtS2bs0.dyn', / ---------------------------------------------------------------------------------- &input fildyn = 'PtS2bs0.dyn', zasr = 'simple', flfrc = 'PtS2bs0.fc', / ------------------------------------------------------------------------------- &input asr = 'simple', amass(1) = 195.08, amass(2) = 32.06, flfrc = 'PtS2bs0fc', flfrq = 'PtS2bs0.freq', / 240 0.0000000000 0.0000000000 0.0000000000 1.0 0.0057471264 0.0000000000 0.0000000000 1.0 0.0114942529 0.0000000000 0.0000000000 1.0 0.0172413793 0.0000000000 0.0000000000 1.0 0.0229885057 0.0000000000 0.0000000000 1.0 0.0287356322 0.0000000000 0.0000000000 1.0 : : : :
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