[QE-users] Self-consistency does not converge

[Gui Wei]

Dear QE users,
I am trying to optimize the adsorption system that contain Fe2O3 substrate and single-layer graphene.Firstly,I tested the conventional unit cell of Fe2O3 and obtained results close to the experimental data,these results include band gaps、lattice constant and magnetic moment.Then I build the Fe2O3(0001) surface using the experimental lattice size and put the graphene on top of its surface. The under layer of Fe2O3 fixed. After optimization, I found that the first step of self-consistent does not reach convergence. The estimated scf accuracy goes down and then goes up,in an oscillating state.Is there any way to solve this problem?(A method is provided in the user manual to add a few empty bands,but I don't understand why did this).




&control
    calculation  = 'relax',
    prefix='Fe2O3Grtop1',
    pseudo_dir = '/public/home/duan1/GuiWei/pseudo/',
    outdir='/public/home/duan1/GuiWei/tempdir/'
    tstress = .true.
    tprnfor = .true.
    etot_conv_thr=1.0D-4
    forc_conv_thr=1.0D-3    
/
 &system    
    ibrav=4, 
    celldm(1) =9.297399
    celldm(3) =8.130085
    nat=38, 
    ntyp=4, 
    nspin = 2 
    starting_magnetization(1) =0.0
    starting_magnetization(2) =0.0
    starting_magnetization(3) =0.5
    starting_magnetization(4) =-0.5
    occupations='smearing',
    smearing='mp',
    degauss=0.01,
    ecutwfc =40.0
    ecutrho =400.0
    lda_plus_u=.true. 
    Hubbard_U(3)=5.0,
    Hubbard_U(4)=5.0,
    Hubbard_J0(3)=1.0
    Hubbard_J0(4)=1.0
    vdw_corr='DFT-D'     
    london_s6 = 0.75     
/
&electrons
    conv_thr =  1.0d-6
    mixing_beta = 0.2
    mixing_ndim=16
    mixing_mode = 'local-TF'
    electron_maxstep=200
    mixing_fixed_ns = 0
/
&IONS
  ion_dynamics='bfgs'
/
ATOMIC_SPECIES
C   12.0107  c_pbe_v1.2.uspp.F.UPF
O   16.00    o_pbe_v1.2.uspp.F.UPF
Fe1  55.847  fe_pbe_v1.5.uspp.F.UPF
Fe2  55.847  fe_pbe_v1.5.uspp.F.UPF
ATOMIC_POSITIONS  crystal
  C   0.0000000000000001  -0.0000000000000013   0.4578339910618399
  C   0.1666664999999976   0.3333334999999993   0.4578339910618399
  C   0.4999999999999998  -0.0000000000000004   0.4578339910618399
  C   0.6666664999999977   0.3333334999999984   0.4578339910618399
  C  -0.0000000000000031   0.4999999999999969   0.4578339910618399
  C   0.1666664999999978   0.8333334999999984   0.4578339910618399
  C   0.4999999999999975   0.5000000000000000   0.4578339910618399
  C   0.6666664999999961   0.8333334999999984   0.4578339910618399
  O   0.2999999999999977  -0.0000000000000013   0.1171837107154874 0 0 0
  O   0.9666669999999991   0.3333329999999979   0.2371599867798649 0 0 0
  O   0.6333330000000009   0.6666669999999995   0.3571366227734300
  O   0.0000000000000000   0.2999999999999998   0.1171837107154874 0 0 0
  O   0.6666669999999983   0.6333329999999995   0.2371599867798649 0 0 0
  O   0.3333330000000006   0.9666670000000002   0.3571366227734298
  O   0.6999999999999989   0.6999999999999993   0.1171837107154873 0 0 0
  O   0.3666669999999980   0.0333329999999985   0.2371599867798649 0 0 0
  O   0.0333330000000000   0.3666669999999983   0.3571366227734300
  O   0.6999999999999993  -0.0000000000000004   0.2971483047766476
  O   0.3666669999999997   0.3333329999999992   0.0571953927187046 0 0 0
  O   0.0333330000000014   0.6666669999999995   0.1771720287122701 0 0 0
  O   0.0000000000000009   0.6999999999999997   0.2971483047766476
  O   0.6666669999999978   0.0333329999999976   0.0571953927187046 0 0 0
  O   0.3333329999999997   0.3666669999999979   0.1771720287122701 0 0 0
  O   0.2999999999999982   0.2999999999999998   0.2971483047766476
  O   0.9666669999999985   0.6333329999999995   0.0571953927187046 0 0 0
  O   0.6333329999999990   0.9666669999999997   0.1771720287122701 0 0 0
 Fe1  0.6666670000000005   0.3333330000000001   0.0949879574715482 0 0 0
 Fe1  0.3333330000000006   0.6666669999999995   0.2149645934651138 0 0 0
 Fe1  0.0000000000000000   0.0000000000000004   0.3349408695294908
 Fe1  0.0000000000000000   0.0000000000000000   0.0793911459626437 0 0 0
 Fe1  0.3333330000000006   0.6666669999999999   0.3193440580205864
 Fe1  0.6666669999999997   0.3333330000000001   0.1993674220270211 0 0 0
 Fe2  0.0000000000000000   0.0000000000000000   0.1549762754683309 0 0 0
 Fe2  0.3333330000000002   0.6666669999999995   0.0349999994039536 0 0 0
 Fe2  0.6666669999999991   0.3333329999999974   0.2749525515327084
 Fe2  0.0000000000000000   0.0000000000000004   0.2593557400238039 0 0 0
 Fe2  0.3333330000000002   0.6666669999999999   0.1393794639594265 0 0 0
 Fe2  0.6666669999999979   0.3333329999999983   0.3793320160881810
K_POINTS automatic
5  5  1  0  0  0








iteration #  1     estimated scf accuracy    <    8498.59677503 Ry
iteration #  2     estimated scf accuracy    <    7643.63024761 Ry
...
iteration # 25     estimated scf accuracy    <      15.43345367 Ry
iteration # 26     estimated scf accuracy    <      82.13161991 Ry
...
iteration #192     estimated scf accuracy    <      21.66486605 Ry
iteration #193     estimated scf accuracy    <      27.45648986 Ry
...



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