[Pw_forum] Convergence Problem

[孙阳]

Dear All,

When I do the calculation of the electronic structure of slab
Palladium under the external electric field,
convergence problems appear. The typical problem is that the estimated
scf accuracy value drop down
down and bounce back. It seems that the calculation does not know
where the system would go for
minimizing the total energy. The electric field that I applied is
saw-tooth like one. I tried many things like
increasing the mixing_ndim, decreasing the mixing_betta to 0.1, adding
empty bands changing the mixing
mode and even increase the degauss. But, none of them would work for
the scf accuracy oscillating problem.
Below is the input file. Any suggestion is highly appreciated.




&control
    calculation='scf'
    restart_mode='from_scratch',
    pseudo_dir = '$PSEUDO_DIR/',
    outdir='$TMP_DIR/'
    prefix='Pd'
    tefield = .true.
    dipfield = .true.
    nstep = 300

 /
 &system
    ibrav = 6
    celldm(1) = 7.3331
    nspin = 2
    celldm(3) = 4.5
    edir = 3
    emaxpos=0.72
    eopreg=0.28
    eamp = -0.001944
    starting_magnetization=0.05
    ntyp = 1
    nat= 14
    ecutwfc = 25.0,
    ecutrho = 500.0,
    occupations='smearing',
    degauss=0.2
    nbnd=160
 /

 &electrons
    conv_thr = 1.0e-4
    mixing_mode='local-TF'
    mixing_beta = 0.05
    mixing_ndim = 12

 /
ATOMIC_SPECIES
 Pd  100  Pd.pz-nd-rrkjus.UPF
ATOMIC_POSITIONS
Pd       0.500000000   0.000000000  -1.496126804
Pd       0.000000000   0.500000000  -1.496126804
Pd       0.000000000   0.000000000  -1.002542052
Pd       0.500000000   0.500000000  -1.002542051
Pd       0.500000000   0.000000000  -0.501470158
Pd       0.000000000   0.500000000  -0.501470158
Pd       0.000000000   0.000000000   0.000000000
Pd       0.500000000   0.500000000   0.000000000
Pd       0.500000000   0.000000000   0.501470158
Pd       0.000000000   0.500000000   0.501470158
Pd       0.000000000   0.000000000   1.002542052
Pd       0.500000000   0.500000000   1.002542051
Pd       0.500000000   0.000000000   1.496126804
Pd       0.000000000   0.500000000   1.496126804




K_POINTS (automatic)
 8 8 1 0 0 0



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University of Nebraska at Lincoln