Dear colleagues,
we have tried to perfom band structure DFT-calculation of crystall SrTiO3 with hybrid functionals.
When we run tests with silicon from the QE package it was OK.
But when we tried SrTiO3 following to the "fake" procedure in Si example, we've got sharp peaks in band structure graph.
We have used PBE0 and HSE functionals with US pseudopotentials. The result was the same.
Furthermore, despite we used nqx1 = 2 nqx2 = 2 nqx3 = 2 in scf-input,
in scf-output there is the record: EXX: q-point mesh: 1 1 1
Input-file:
&CONTROL
calculation = "scf"
restart_mode='from_scratch',
prefix = 'SrTiO3',
nstep = 900,
max_seconds = 8.64000e+04
pseudo_dir = "/home/QuantumEspresso/pseudo",
wf_collect = .true.
etot_conv_thr = 1.0d-8
verbosity ='high'
/
&SYSTEM
ibrav = 1,
a = 3.8931e+00,
nat=5,
ntyp=3,
occupations='smearing',
smearing ='gauss',
degauss = 0.005,
nspin= 1
ecutwfc = 55.0d0
ecutrho = 580.d0
input_dft = 'hse',
nqx1 = 2
nqx2 = 2
nqx3 = 2
/
&ELECTRONS
electron_maxstep = 800
conv_thr = 1.0d-8
mixing_beta = 0.3
/
&IONS
ion_dynamics ='bfgs'
/
&CELL
/
ATOMIC_SPECIES
O 15.9994 O.pbesol-n-rrkjus_psl.1.0.0.UPF
Sr 87.6200 Sr.pbesol-spn-rrkjus_psl.1.0.0.UPF
Ti 47.8670 Ti.pbesol-spn-rrkjus_psl.1.0.0.UPF
ATOMIC_POSITIONS {crystal}
O 0.5 0.0 0.5
O 0.5 0.5 0.0
O 0.0 0.5 0.5
Sr 0.0 0.0 0.0
Ti 0.5 0.5 0.5
K_POINTS automatic
8 8 8 0 0 0
ADDITIONAL_K_POINTS tpiba_b
8
0.0000000000 0.0000000000 0.0000000000 20 ! GAMMA
0.0000000000 0.5000000000 0.0000000000 20 ! X
0.5000000000 0.5000000000 0.0000000000 28 ! M
0.0000000000 0.0000000000 0.0000000000 36 ! GAMMA
0.5000000000 0.5000000000 0.5000000000 28 ! R
0.0000000000 0.5000000000 0.0000000000 0 ! X
0.5000000000 0.5000000000 0.0000000000 20 ! M
0.5000000000 0.5000000000 0.5000000000 0 ! R
Would you answer my question, is there a way to get appropriate band structure picture with hybrid functional using the "fake" procedure?
Regards,
Gavrikov Anton,
PhD, researcher,
Saint-Petersburg State University.
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