Dear QE community,
I meet a strange SCF convergence problem for my monolayer \alpha-RuCl3 system.
I’m conducting GGA+SOC+U+Constrained DFT in QE-7.0.
But the estimated SCF accuracy for my system is considerably large in the first
and the following steps, more enormous than 10000 Ry.
I have tried many methods such as modifying the mixing scheme from plain to TF,
tuning the degauss, and trying different occupation and smearing schemes.
I also tried to start from the GGA+LSDA+U case, which works well and gets
converged in 700 steps.
But no scheme works for GGA+SOC+U+Constrained DFT.
And even for just the GGA+SOC+U case, I can't obtain a small SCF accuracy.
I’d like to know what I can do for it and get a normal SCF process.
My input is in the following.
This structure was obtained from OpenMX, another DFT package based on the LCAO
method.
&CONTROL
calculation='scf',
prefix='mono',
pseudo_dir='/home/zhang/calculation/rucl3/pseudo',
restart_mode='from_scratch',
outdir='./',
verbosity='high',
/
&SYSTEM
ibrav= 0,
nat= 16, ntyp= 3,
occupations = 'smearing',
smearing='mp', degauss=1d-9,
ecutwfc= 100,
noncolin=.true.,lspinorb=.true.,
starting_magnetization(1)= 0.5,
starting_magnetization(2)= 0.5,
starting_magnetization(3)= 0.0,
lda_plus_u = .true.,
lda_plus_u_kind = 1,
U_projection_type = 'ortho-atomic',
Hubbard_U(1)=1.5,
Hubbard_U(2)=1.5
/
&ELECTRONS
electron_maxstep = 1600
conv_thr = 1.0d-8
mixing_mode = 'TF'
mixing_beta = 4.0d-2
mixing_ndim = 20
startingpot = 'atomic'
diagonalization = 'david'
/
ATOMIC_SPECIES
Ruu 101.07 Ru.rel-pbe-spn-kjpaw_psl.1.0.0.UPF
Rud 101.07 Ru.rel-pbe-spn-kjpaw_psl.1.0.0.UPF
Cl 35.45 Cl.pbe-n-kjpaw_psl.1.0.0.UPF
ATOMIC_POSITIONS {angstrom}
Ruu -2.4165100 0.0119000 2.4251100
Ruu 0.0032200 0.0119000 0.0053700
Cl 2.3833500 -0.0499700 0.0334100
Cl -2.3884800 -0.0499700 4.8052300
Cl -0.0381100 0.0580100 2.3837700
Cl -2.3751800 -0.0342100 0.0467100
Cl -2.4518700 -2.3681500 2.5014800
Cl 0.0796000 -2.3681500 -0.0299800
Rud 0.0105400 2.4538100 -2.4511300
Rud 2.4302700 2.4538100 -4.8708700
Cl 4.8104000 2.3919400 -4.8428300
Cl 0.0385700 2.3919400 -0.0710100
Cl 2.3889400 2.4999200 -2.4924700
Cl 0.0518700 2.4077000 -4.8295300
Cl -0.0248200 0.0737600 -2.3747600
Cl 2.5066500 0.0737600 -4.9062200
CELL_PARAMETERS {angstrom}
4.8541000 4.8838200 -9.7524800
-4.8762300 2.4419100 2.4270500
10.0203300 10.0185400 10.0203300
K_POINTS {automatic}
6 12 1 0 0 0
The following is part of the output
total energy = -2977.28363823 Ry estimated scf accuracy < 529768.11044287 Ry
total energy = -2977.28363823 Ry estimated scf accuracy < 529768.11044287 Ry
total energy = -3184.06809008 Ry estimated scf accuracy < 814811.34802588 Ry
total energy = -3274.94372181 Ry estimated scf accuracy < 746852.52429958 Ry
total energy = -3307.21972156 Ry estimated scf accuracy < 752237.62011255 Ry
total energy = -3291.26999775 Ry estimated scf accuracy < 757458.22549562 Ry
total energy = -3349.60629608 Ry estimated scf accuracy < 765501.04417510 Ry
total energy = -3337.49045478 Ry estimated scf accuracy < 768896.10678680 Ry
total energy = -3287.13640144 Ry estimated scf accuracy < 762797.72531670 Ry
total energy = -3333.32846680 Ry estimated scf accuracy < 751861.05720886 Ry
total energy = -3341.65785225 Ry estimated scf accuracy < 754604.69881806 Ry
total energy = -3350.72599779 Ry estimated scf accuracy < 749241.08182438 Ry
total energy = -3366.01560869 Ry estimated scf accuracy < 741018.08470080 Ry
With best regards
Lingzhi Zhang
Department of Applied Physics,
University of Tokyo, Japan
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