[QE-users] Optimization does not converge

[Gui Wei]

Dear QE users,
I am trying to optimize a single-layer graphene connected to a hydroxyl group.After 48 scf cycles,the optimization result has never reached the convergence value,the force of some atoms is always greater than the convergence threshold.But when I connect an epoxy group instead of a hydroxyl group on the graphene sheet, the optimization can reach convergence after 24 scf cycles.Does anyone know the reason for this?
Any suggestions would be greatly appreciated.
Thank you.


 &control
    calculation  = 'relax',
    prefix='QJ1GO',
    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= 0, 
    nat=66, 
    ntyp=3,
        
    occupations='smearing',
    smearing='mp',
    degauss=0.02,


    ecutwfc =40.0
    ecutrho =320.0
    
    vdw_corr='DFT-D'     
    london_s6 = 0.75


/
&electrons
    conv_thr =  1.0d-8
    mixing_beta = 0.2
    mixing_mode = 'local-TF'
    mixing_ndim=16
    electron_maxstep=200
/
&IONS
  ion_dynamics='bfgs'
/
CELL_PARAMETERS angstrom
19.680000000000003       0.000000000000010       0.000000000000000
 0.000000000000000       8.521689973238882       0.000000000000000
 0.000000000000000       0.000000000000000      25.000000000000000
ATOMIC_SPECIES
C  12.0107   C.pbe-rrkjus.UPF
O   16.00    O.pbe-rrkjus.UPF
H   1.00     H.pbe-rrkjus.UPF
ATOMIC_POSITIONS  crystal
  C   0.0000000000000000   0.0000000000000000   0.2164000000000000
  C   0.1250000000000000  -0.0000000000000000   0.2164000000000000
  C   0.0625000000000000   0.2499999999999999   0.2164000000000000
  C   0.0000000000000000   0.4999999999999999   0.2164000000000000
  C   0.2500000000000000  -0.0000000000000002   0.2164000000000000
  C   0.1875000000000000   0.2499999999999999   0.2164000000000000
  C   0.1250000000000000   0.4999999999999998   0.2164000000000000
  C   0.0624999999999998   0.7499999999999989   0.2164000000000000
  C   0.3750000000000000  -0.0000000000000002   0.2164000000000000
  C   0.3125000000000000   0.2500000000000000   0.2164000000000000
  C   0.2500000000000000   0.4999999999999999   0.2164000000000000
  C   0.1875000000000000   0.7499999999999989   0.2164000000000000
  C   0.5000000000000000  -0.0000000000000002   0.2164000000000000
  C   0.4375000000000000   0.2500000000000000   0.2164000000000000
  C   0.3750000000000000   0.4999999999999999   0.2164000000000000
  C   0.3125000000000000   0.7499999999999988   0.2164000000000000
  C   0.6250000000000000  -0.0000000000000004   0.2164000000000000
  C   0.5625000000000000   0.2500000000000000   0.2164000000000000
  C   0.5000000000000000   0.4999999999999999   0.2164000000000000
  C   0.4375000000000000   0.7499999999999988   0.2164000000000000
  C   0.7500000000000000  -0.0000000000000004   0.2164000000000000
  C   0.6875000000000000   0.2499999999999999   0.2164000000000000
  C   0.6250000000000000   0.4999999999999999   0.2164000000000000
  C   0.5625000000000000   0.7499999999999988   0.2164000000000000
  C   0.8750000000000000  -0.0000000000000004   0.2164000000000000
  C   0.8125000000000000   0.2499999999999990   0.2164000000000000
  C   0.7500000000000000   0.4999999999999999   0.2164000000000000
  C   0.6875000000000000   0.7499999999999989   0.2164000000000000
  C   0.9375000000000000   0.2499999999999990   0.2164000000000000
  C   0.8750000000000000   0.5000000000000000   0.2164000000000000
  C   0.8125000000000000   0.7499999999999988   0.2164000000000000
  C   0.9375000000000000   0.7499999999999988   0.2164000000000000
  C   0.0624999725702591   0.0833332967603452   0.2164000000000000
  C  -0.0000000274297411   0.3333332967603450   0.2164000000000000
  C   0.1874999725702590   0.0833332967603452   0.2164000000000000
  C   0.1249999725702590   0.3333332967603450   0.2164000000000000
  C   0.0624999725702589   0.5833332967603438   0.2164000000000000
  C  -0.0000000274297409   0.8333332967603447   0.2164000000000000
  C   0.3124999725702590   0.0833332967603452   0.2164000000000000
  C   0.2499999725702590   0.3333332967603450   0.2164000000000000
  C   0.1874999725702590   0.5833332967603448   0.2164000000000000
  C   0.1249999725702590   0.8333332967603447   0.2164000000000000
  C   0.4374999725702590   0.0833332967603452   0.2164000000000000
  C   0.3749999725702590   0.3333332967603450   0.2164000000000000
  C   0.3124999725702590   0.5833332967603448   0.2164000000000000
  C   0.2499999725702590   0.8333332967603447   0.2164000000000000
  C   0.5624999725702590   0.0833332967603451   0.2164000000000000
  C   0.4999999725702591   0.3333332967603449   0.2164000000000000
  C   0.4374999725702590   0.5833332967603438   0.2164000000000000
  C   0.3749999725702590   0.8333332967603447   0.2164000000000000
  C   0.6874999725702590   0.0833332967603451   0.2164000000000000
  C   0.6249999725702590   0.3333332967603450   0.2164000000000000
  C   0.5624999725702590   0.5833332967603447   0.2164000000000000
  C   0.4999999725702591   0.8333332967603448   0.2164000000000000
  C   0.8124999725702590   0.0833332967603451   0.2164000000000000
  C   0.7499999725702590   0.3333332967603450   0.2164000000000000
  C   0.6874999725702600   0.5833332967603440   0.2164000000000000
  C   0.6249999725702590   0.8333332967603438   0.2164000000000000
  C   0.9374999725702590   0.0833332967603450   0.2164000000000000
  C   0.8749999725702590   0.3333332967603450   0.2164000000000000
  C   0.8124999725702600   0.5833332967603438   0.2164000000000000
  C   0.7499999725702590   0.8333332967603438   0.2164000000000000
  C   0.9374999725702590   0.5833332967603438   0.2164000000000000
  C   0.8749999725702601   0.8333332967603448   0.2164000000000000
  O   0.5008325506691220   0.4975899051684459   0.2743438844378600
  H   0.4505865611121930   0.4983293698599460   0.2875531708238770
K_POINTS automatic
2  2  1  0  0  0


Wei gui
School of Mechanical Engineering，Chongqing University, China



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