[QE-users] Convergence Issues?

Stephen Zhang lolzen at berkeley.edu
Mon Jan 25 07:30:16 CET 2021


Hi Everyone,

I'm currently having issues achieving convergence for my SCF calculations
with SOC on nickel intercalated TaSe2. Since it is a metal, I've tried
increasing the total number of bands and that didn't really work. I've also
tried using local Thomas Fermi mixing due to address its elongated unit
cell, as well as increased the ecutwfc and k-point density. So far the best
scf accuracy I can achieve it ~2e-6 eV. One thing I've noticed is when the
scf accuracy reaches 2e-6 eV, it will begin to oscillate from between 3e-6
to 2e-6 eV. I'm not sure what else to try. Anyways, thank you for reading
this post and if you have any suggestions or tips, I would greatly
appreciate hearing them.

Here is my input
#################################################
&CONTROL
    calculation='scf'
    prefix='TaNiSe'
    restart_mode='from_scratch'
    outdir='./outdir/'
    pseudo_dir='/global/scratch/lolzen/qe-6.7/SSSP_precision_pseudos/'
/
&SYSTEM
    ibrav = 0, celldm(1)=12.991867,
    nat = 26, ntyp = 3,
    ecutwfc = 70,
    ecutrho = 700,
    occupations = 'smearing', degauss = 0.01, smearing = 'mv'
    nbnd = 660
    noncolin=.true.
    lspinorb=.true.
    starting_magnetization(1)=0.8
/
&ELECTRONS
    mixing_mode='local-TF'
    conv_thr = 1.0d-9,
/
ATOMIC_SPECIES
  Ni    58.6934    Ni.rel-pbe-spn-kjpaw_psl.1.0.0.UPF
  Ta    180.94788  Ta.rel-pbe-spfn-kjpaw_psl.1.0.0.UPF
  Se    78.96      Se.rel-pbe-dn-kjpaw_psl.1.0.0.UPF

CELL_PARAMETERS (alat)
   1.004956653   0.000000000   0.000000000
  -0.502478327   0.870317991   0.000000000
   0.000000000   0.000000000   1.808363590

ATOMIC_POSITIONS (crystal)
Ni            0.0000000000       -0.0000000000        0.0000000000
Ni           -0.0000000000       -0.0000000000        0.5000000000
Ta            0.0000000000        0.0000000000        0.7500000000
Ta            0.0000000000       -0.0000000000        0.2500000000
Ta            0.9795988645        0.4897994323        0.2500000000
Ta            0.5102005677        0.4897994323        0.2500000000
Ta            0.5102005677        0.0204011355        0.2500000000
Ta            0.0204011355        0.5102005677        0.7500000000
Ta            0.4897994323        0.5102005677        0.7500000000
Ta            0.4897994323        0.9795988645        0.7500000000
Se            0.6666666700        0.3333333300        0.3922175119
Se            0.3333333300        0.6666666700        0.6077824881
Se            0.3333333300        0.6666666700        0.8922175119
Se            0.6666666700        0.3333333300        0.1077824881
Se            0.6624039120        0.8312019560        0.3820242878
Se            0.1687980440        0.8312019560        0.3820242878
Se            0.1687980440        0.3375960880        0.3820242878
Se            0.3375960880        0.1687980440        0.6179757122
Se            0.8312019560        0.1687980440        0.6179757122
Se            0.8312019560        0.6624039120        0.6179757122
Se            0.3375960880        0.1687980440        0.8820242878
Se            0.8312019560        0.1687980440        0.8820242878
Se            0.8312019560        0.6624039120        0.8820242878
Se            0.6624039120        0.8312019560        0.1179757122
Se            0.1687980440        0.8312019560        0.1179757122
Se            0.1687980440        0.3375960880        0.1179757122


K_POINTS automatic
 13 13 7 0 0 0
#################################################
End of input

Last few iterations of output
#################################################
 Davidson diagonalization with overlap
     ethr =  5.54E-10,  avg # of iterations =  4.2

     total cpu time spent up to now is    62608.6 secs

     total energy              =  -17171.63213074 Ry
     estimated scf accuracy    <       0.00000313 Ry

     total magnetization       =     0.00     0.00     2.38 Bohr mag/cell
     absolute magnetization    =     2.89 Bohr mag/cell

     iteration # 34     ecut=    70.00 Ry     beta= 0.70
     Davidson diagonalization with overlap
     ethr =  5.54E-10,  avg # of iterations =  4.0

     total cpu time spent up to now is    64690.6 secs

     total energy              =  -17171.63214316 Ry
     estimated scf accuracy    <       0.00000314 Ry

     total magnetization       =    -0.00     0.00     2.38 Bohr mag/cell
     absolute magnetization    =     2.89 Bohr mag/cell

     iteration # 35     ecut=    70.00 Ry     beta= 0.70
     Davidson diagonalization with overlap
     ethr =  5.54E-10,  avg # of iterations =  4.0

     total cpu time spent up to now is    66352.1 secs

     total energy              =  -17171.63194323 Ry
     estimated scf accuracy    <       0.00000339 Ry

     total magnetization       =     0.00    -0.00     2.38 Bohr mag/cell
     absolute magnetization    =     2.89 Bohr mag/cell

     iteration # 36     ecut=    70.00 Ry     beta= 0.70
     Davidson diagonalization with overlap
     ethr =  5.54E-10,  avg # of iterations =  5.3

     total cpu time spent up to now is    68566.2 secs

     total energy              =  -17171.63217226 Ry
     estimated scf accuracy    <       0.00000263 Ry

     total magnetization       =    -0.00    -0.00     2.38 Bohr mag/cell
     absolute magnetization    =     2.87 Bohr mag/cell

     iteration # 37     ecut=    70.00 Ry     beta= 0.70
     Davidson diagonalization with overlap
     ethr =  5.18E-10,  avg # of iterations =  5.2

     total cpu time spent up to now is    70693.8 secs

     total energy              =  -17171.63216140 Ry
     estimated scf accuracy    <       0.00000268 Ry

     total magnetization       =     0.00     0.00     2.38 Bohr mag/cell
     absolute magnetization    =     2.87 Bohr mag/cell

     iteration # 38     ecut=    70.00 Ry     beta= 0.70
     Davidson diagonalization with overlap
     ethr =  5.18E-10,  avg # of iterations =  6.2

     total cpu time spent up to now is    73119.5 secs

     total energy              =  -17171.63204582 Ry
     estimated scf accuracy    <       0.00000351 Ry

     total magnetization       =    -0.00     0.00     2.38 Bohr mag/cell
     absolute magnetization    =     2.92 Bohr mag/cell

     iteration # 39     ecut=    70.00 Ry     beta= 0.70
     Davidson diagonalization with overlap
     ethr =  5.18E-10,  avg # of iterations =  4.5

     total cpu time spent up to now is    75281.8 secs

     total energy              =  -17171.63218978 Ry
     estimated scf accuracy    <       0.00000285 Ry

     total magnetization       =     0.00    -0.00     2.38 Bohr mag/cell
     absolute magnetization    =     2.89 Bohr mag/cell

     iteration # 40     ecut=    70.00 Ry     beta= 0.70
     Davidson diagonalization with overlap
     ethr =  5.18E-10,  avg # of iterations =  6.0

     total cpu time spent up to now is    77599.0 secs

     total energy              =  -17171.63247747 Ry
     estimated scf accuracy    <       0.00000310 Ry

     total magnetization       =    -0.00     0.00     2.38 Bohr mag/cell
     absolute magnetization    =     2.89 Bohr mag/cell

     iteration # 41     ecut=    70.00 Ry     beta= 0.70
     Davidson diagonalization with overlap
#################################################
Thank you,
Stephen


-- 
*University of California, Berkeley*
*Department of Letter and Sciences*
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