edir=1 and 2 are extremely inefficient in parallel. Use edir=3, rotate your slab. Does it converge without field? Also, your choic is a of k-points looks the opposite of correct: you need many points along the field direction.
-- Lorenzo Paulatto Written on a virtual keyboard with real fingers On Sat, 29 Sep 2018, 20:43 Alex.Durie, <[email protected]> wrote: > Dear experts, > > I am attempting to perform an scf calculation on a semi-infinite slab of > ferromagnetic cobalt surrounded by a vacuum with an electric field applied > perpendicular to the magnetisation, out-of-plane. > > I am struggling to get convergence in the scf cycle. I achieved > satisfactory results using the same geometry and k-points without the field. > > I have attempted to run it with ecutwfc = 30, and ecutrho at its default > value. Now I am attempting ecutwfc = 46, ecutrho = 238 (as recommended in > the header of the pseudopotential file). > > I find in both cases the total energy and Harris-Foulkes estimate are > usually negative, and the estimated scf accuracy is very large, for each > cycle. > > The runtime for larger ecutwfc and ecutrho, is much longer. > > Is there something I'm doing wrong, or do I need to alter my expectations > of runtime? Please see input file below. > > I am running the code with MPI, on 4 cores. At 12 iterations, the CPU time > is 24737.9 secs, the total energy is -377.46347734 Ry, the Harris-Foulkes > estimate is -1293.19368730 Ry and the estimated scf accuracy is < > 3322.28583637 Ry. I have also noticed the "Adding external electric field" > block is duplicated on each cycle, though I suspect that's normal. > > Many thanks > > Alex Durie > PhD student > The Open University > United Kingdom > > &control > calculation='scf' > restart_mode='from_scratch', > pseudo_dir = '/home/alex/QE/pslibrary.1.0.0/pz/PSEUDOPOTENTIALS/', > outdir='./' > prefix='co' > tefield = .true. > dipfield = .true. > / > &system > ibrav = 8, > celldm(1) =4.82388, > celldm(2) =8., > celldm(3) =1., > nat= 5, > ntyp= 1, > ecutwfc = 46.0 > ecutrho = 238.0 > nspin = 2 > occupations='smearing', smearing='cold', degauss=0.02 > starting_magnetization = -1 > nbnd = 45 > edir = 2 > emaxpos = 0.41 > eopreg = 0.59 > eamp = 0.000243 > / > &electrons > electron_maxstep = 500 > diagonalization='cg' > conv_thr = 1.0e-6 > mixing_beta = 0.3 > / > ATOMIC_SPECIES > Co 58.933195 Co.pz-n-kjpaw_psl.1.0.0.UPF > ATOMIC_POSITIONS {bohr} > Co 0.0000000 0.0000000 0.000000 > Co 2.4119400 3.4110000 2.411940 > Co 0.0000000 6.8220000 0.000000 > Co 2.4119400 10.2330000 2.411940 > Co 0.0000000 13.6440000 0.000000 > K_POINTS {automatic} > 16 2 16 0 0 0 > > _______________________________________________ > users mailing list > [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users
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