Dear all, I have read several posts regarding this issue but I am still unable to get the electrical fields calculation in ph.x converged for phonon dispersion calculation. The behavior, which many experience is as follows:
iter # 10 total cpu time : 21241.7 secs av.it.: 1.3 thresh= 6.227E-05 alpha_mix = 0.400 |ddv_scf|^2 = *1.388E-08* iter # 11 total cpu time : 22225.5 secs av.it.: 4.4 thresh= 1.178E-05 alpha_mix = 0.400 |ddv_scf|^2 = * 1.528E-12* iter # 12 total cpu time : 24354.9 secs av.it.: 18.0 thresh= 1.236E-07 alpha_mix = 0.400 |ddv_scf|^2 = *3.025E-07* iter # 13 total cpu time : 25425.8 secs av.it.: 5.7 thresh= 5.500E-05 alpha_mix = 0.400 |ddv_scf|^2 =* 6.748E-08* iter # 14 total cpu time : 26243.8 secs av.it.: 2.9 thresh= 2.598E-05 alpha_mix = 0.400 |ddv_scf|^2 =* 2.569E-08* iter # 15 total cpu time : 27076.0 secs av.it.: 3.3 thresh= 1.603E-05 alpha_mix = 0.400 |ddv_scf|^2 = 6.075E-08 iter # 16 total cpu time : 27797.8 secs av.it.: 2.3 thresh= 2.465E-05 alpha_mix = 0.400 |ddv_scf|^2 = 3.101E-07 iter # 17 total cpu time : 29230.3 secs av.it.: 9.7 thresh= 5.569E-05 alpha_mix = 0.400 |ddv_scf|^2 = 2.663E-07 iter # 18 total cpu time : 30358.8 secs av.it.: 6.5 thresh= 5.160E-05 alpha_mix = 0.400 |ddv_scf|^2 = 3.309E-07 iter # 19 total cpu time : 31460.7 secs av.it.: 6.0 thresh= 5.752E-05 alpha_mix = 0.400 |ddv_scf|^2 = 8.663E-08 that is, after originally apparently converging it starts oscillating between 1E-8 and 1E-7 until 100 iterations. Reducing alpha_mix down to 0.01 does not alleviate this problem. Interestingly this does not happen for Gamma point only: Electric Fields Calculation iter # 1 total cpu time : 3714.8 secs av.it.: 8.3 thresh= 1.000E-02 alpha_mix = 0.700 |ddv_scf|^2 = 1.982E-08 iter # 2 total cpu time : 5447.0 secs av.it.: 19.2 thresh= 1.408E-05 alpha_mix = 0.700 |ddv_scf|^2 = 1.787E-08 iter # 3 total cpu time : 7174.1 secs av.it.: 18.0 thresh= 1.337E-05 alpha_mix = 0.700 |ddv_scf|^2 = 1.003E-09 iter # 4 total cpu time : 8856.3 secs av.it.: 18.0 thresh= 3.167E-06 alpha_mix = 0.700 |ddv_scf|^2 = 9.881E-11 iter # 5 total cpu time : 10554.6 secs av.it.: 18.3 thresh= 9.940E-07 alpha_mix = 0.700 |ddv_scf|^2 = 1.223E-10 iter # 6 total cpu time : 12142.6 secs av.it.: 16.9 thresh= 1.106E-06 alpha_mix = 0.700 |ddv_scf|^2 = 2.022E-12 iter # 7 total cpu time : 13919.5 secs av.it.: 18.7 thresh= 1.422E-07 alpha_mix = 0.700 |ddv_scf|^2 = 3.477E-12 ... ... iter # 12 total cpu time : 22432.3 secs av.it.: 17.7 thresh= 1.628E-09 alpha_mix = 0.700 |ddv_scf|^2 = 1.601E-16 iter # 13 total cpu time : 24072.0 secs av.it.: 17.3 thresh= 1.265E-09 alpha_mix = 0.700 |ddv_scf|^2 = *1.580E-17* even with alpha_mix=0.7 (default value). The system is a relaxed CsPbBr3 (I attach the input below). Anyone with more experience an idea what to do here? Have a good weekend everyone! Chris &control calculation = 'scf' prefix='cspbbr3', pseudo_dir = '../../pseudo', outdir='./' wf_collect=.true. verbosity='high' nstep = 500 / &SYSTEM ibrav = 0 A = 8.24400 nat = 20 ntyp = 3 ecutwfc = 100, occupations='fixed' / &ELECTRONS conv_thr=1e-17 diago_thr_init=1e-3 diagonalization='cg' / ATOMIC_SPECIES Pb 207.20000 Pb_ONCV_PBE-Chris.UPF Cs 132.90500 Cs_ONCV_PBE-Chris.UPF Br 79.90400 Br_ONCV_PBE-Chris.UPF K_POINTS automatic 9 9 9 0 0 0 CELL_PARAMETERS (alat= 15.57890224) 1.034550924 0.000000000 0.000000000 0.000000000 1.442904322 0.000000000 0.000000000 0.000000000 1.002723182 ATOMIC_POSITIONS (crystal) Pb 0.000000000 0.500000000 0.000000000 Pb 0.500000000 0.000000000 0.500000000 Pb 0.500000000 0.500000000 0.500000000 Pb 0.000000000 0.000000000 0.000000000 Cs 0.557073579 0.250000000 0.015983762 Cs 0.942926421 0.750000000 0.515983762 Cs 0.442926421 0.750000000 0.984016238 Cs 0.057073579 0.250000000 0.484016238 Br 0.293064750 0.462313289 0.204460039 Br 0.206935250 0.962313289 0.704460039 Br 0.206935250 0.537686711 0.704460039 Br 0.706935250 0.962313289 0.795539961 Br 0.706935250 0.537686711 0.795539961 Br 0.793064750 0.037686711 0.295539961 Br 0.793064750 0.462313289 0.295539961 Br 0.293064750 0.037686711 0.204460039 Br 0.013732263 0.750000000 0.072407914 Br 0.486267737 0.250000000 0.572407914 Br 0.986267737 0.250000000 0.927592086 Br 0.513732263 0.750000000 0.427592086 &inputph prefix = 'cspbbr3', recover = .false. amass(1) = 207.20000 amass(2) = 132.90500 amass(3) = 79.90400 epsil = .true., fildyn = 'cspbbr3.dyn', ldisp = .true. nq1=4, nq2=3, nq3=4 fildvscf = 'dvscf' tr2_ph = 1.0d-12, alpha_mix(1)=0.01 alpha_mix(2)=0.01 alpha_mix(3)=0.01 alpha_mix(4)=0.01 / -- Postdoctoral Researcher Center for Quantum Nanoscience, Institute for Basic Science Ewha Womans University, Seoul, South Korea
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