Dear everyone, I have a convergency problem facing the pw.x after version 5.0.2
The example input is given in the last section. The structure is a bcc-like supercell containing Fe and Cu atoms (relaxed) (with GBRV uspp). The structure can be run properly with smearing, the problem comes from "tetrahedra" occupation. If I use a non-offset k point mesh, as given in the input, the convergency would get stuck around 1E-6~1E-8 Ry, never get better like most other supercells of Fe and Cu. The problem can be solved by offset the k mesh. However, my local mentors do not suggest me to do so. Because we have lots of different supercells, the offseted k mesh would give very different centering k point in different supercells, it would appear to be trouble if I compare their energies. (btw, what is your opinions on this?) The problem can also be solved by increasing the size of k mesh, but still, not cheap and absolute necessary for the calculation of lots supercells. However, in version 5.0.2, there is no such problem, and convergency can be achieved quickly (if I rerun [in post 5.0.2 versions] starting from the converged charge density [by v 5.0.2], convergency still cannot be achieved ). That's why I'm asking for help here, before I turn to other solutions. So far, I tried to change number of bands, mixing beta, and parallel running parameter...all those appear to be irrelevant. Only k mesh would change the result. Your suggestions and help is appreciated. Yi Wang Nanjing university of Science and Technology &control calculation = 'scf' , prefix = 'pwscf' , outdir = './temp-p_t/' , pseudo_dir = '/home/sim/pot/pwscf/' , restart_mode = from_scratch , disk_io= 'none' / &system ibrav = 0 , ecutwfc = 40 , ecutrho = 400 , occupations = 'tetrahedra' , nspin=2, nbnd= 120, nat = 12 , ntyp = 2 , starting_magnetization( 1 )= 0.01, starting_magnetization( 2 )= 0.26, use_all_frac=.true. / &electrons conv_thr = 1d-9 , diagonalization = 'david' , mixing_mode = 'local-TF' , startingpot = 'atomic' , startingwfc = 'atomic+random' mixing_beta = 0.12 , mixing_ndim = 16, diago_david_ndim=4 / CELL_PARAMETERS bohr 5.689675841 0.000000000 0.000000000 0.000000000 -10.558955237 0.000000000 0.000000000 0.000000000 -15.996363568 ATOMIC_SPECIES Cu 63.546 cu_pbe_v1.2.uspp.F.UPF Fe 55.845 fe_pbe_v1.5.uspp.F.UPF ATOMIC_POSITIONS crystal Fe 1.000000000 0.498189104 0.666054422 Fe 0.500000000 0.251812190 0.500611021 Fe 1.000000000 0.003971761 0.664566351 Fe 0.500000000 0.746028153 0.502102015 Fe 1.000000000 0.500799770 0.333333330 Fe 0.500000000 0.249203627 0.833333320 Cu 1.000000000 0.998064252 0.333333150 Cu 0.500000000 0.751929936 0.833333540 Fe 0.500000000 0.251812380 0.166055619 Fe 0.500000000 0.746028003 0.164564485 Fe 1.000000000 0.498188874 0.000612278 Fe 1.000000000 0.003971951 0.002100469 K_POINTS automatic 12 7 4 0 0 0
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