Hello, I have a difficulty in lattice relaxing of the EuTiO3 material with Quantum Espresso 7.1 version. EuTiO3 material is antiferromagnetic. Eu atom of this material have 4f-shell electrons and spin-polarization. Hence, Hubbard potential U & Hund exchange J values are needed to do "vc-relax". Other papers also use U&J potentials for optimization of this material, and I will give an example of application in one of them.
"Density functional calculations. Our first-principles calculations were carried out using the Vienna ab-initio simulation package (VASP)47 with the Perdew–Burke–Ernzerhof approximation to the exchange correlation functional48. Eu 4f electrons were treated with the GGA+U method, using Dudarev’s approach49, with U=6.0 eV and J=1.0 eV. Default projector augmented wave pseudopotentials were employed. A plane wave cutoff of 500 eV was used and the Brillouin zone was sampled using an 8×8×6 k-point grid."
- Multiferroic quantum criticality, 2019, Multiferroic quantum criticality
I intend to follow the method of the above paper almost similarly. But instead of VASP program, I use Quantum Espresso. I couldn't search paper following the above method with Quantum Espresso.
My input data is as follows:
--------------------------------------------------------------------------------------------
&control
calculation = 'vc-relax'
restart_mode='from_scratch',
prefix='ETO',
pseudo_dir ='/home/dydtlr5506/pseudo',
outdir='./wavefunc'
tstress = .true.
forc_conv_thr = 1.0d-7
dt = 20
disk_io = 'none'
nstep =9910
/
&system
ibrav= 0,
nat=20, ntyp= 4,
ecutwfc = 80.0, ecutrho = 640.0,
occupations = 'smearing',
smearing = 'gaussian'
degauss = 0.0010
nspin = 2
starting_magnetization(1)=0.5
starting_magnetization(2)=-0.5
/ &electrons
mixing_mode = 'plain'
electron_maxstep = 100
conv_thr = 1.0d-13
/
&ions
ion_dynamics = 'bfgs'
/ &cell
cell_dofree='xyz'
cell_dynamics = 'bfgs'
/
ATOMIC_SPECIES
Eu1 151.964 Eu.pbe-spn-kjpaw_psl.1.0.0.UPF
Eu2 151.964 Eu.pbe-spn-kjpaw_psl.1.0.0.UPF
Ti 47.86 Ti.pbe-spn-kjpaw_psl.1.0.0.UPF
O 15.999 O.pbe-n-kjpaw_psl.1.0.0.UPF
K_POINTS {automatic}
6 6 4 0 0 0
CELL_PARAMETERS (angstrom)
5.4810958704672510 0.0000000000000000 0.0000000000000003
0.0000000000000009 5.4810958704672510 0.0000000000000003
0.0000000000000000 0.0000000000000000 7.8763673700122299
ATOMIC_POSITIONS (crystal)
Eu1 0.0000000000000000 0.5000000000000000 0.2500000000000000 1 1 0
Eu2 0.5000000000000000 0.0000000000000000 0.2500000000000000 1 1 0
Eu1 0.5000000000000000 0.0000000000000000 0.7500000000000000 1 1 0
Eu2 0.0000000000000000 0.5000000000000000 0.7500000000000000 1 1 0
Ti 0.5000000000000000 0.5000000000000000 0.5000000000000000 1 1 0
Ti 0.0000000000000000 0.0000000000000000 0.5000000000000000 1 1 0
Ti 0.0000000000000000 0.0000000000000000 0.0000000000000000 1 1 0
Ti 0.5000000000000000 0.5000000000000000 0.0000000000000000 1 1 0
O 0.5000000000000000 0.5000000000000000 0.2500000000000000 1 1 0
O 0.0000000000000000 0.0000000000000000 0.2500000000000000 1 1 0
O 0.7079342699999996 0.2079342699999996 0.0000000000000000 1 1 0
O 0.7920657300000004 0.2920657300000004 0.5000000000000000 1 1 0
O 0.2920657300000004 0.2079342699999996 0.5000000000000000 1 1 0
O 0.2079342699999996 0.2920657300000004 0.0000000000000000 1 1 0
O 0.0000000000000000 0.0000000000000000 0.7500000000000000 1 1 0
O 0.5000000000000000 0.5000000000000000 0.7500000000000000 1 1 0
O 0.2079342699999995 0.7079342699999996 0.5000000000000000 1 1 0
O 0.2920657300000005 0.7920657300000004 0.0000000000000000 1 1 0
O 0.7920657300000004 0.7079342699999996 0.0000000000000000 1 1 0
O 0.7079342699999996 0.7920657300000004 0.5000000000000000 1 1 0
HUBBARD (ortho-atomic)
U Eu1-4f 6.0
J0 Eu1-4f 1.0
U Eu2-4f 6.0
Jo Eu2-4f 1.0
--------------------------------------------------------------------------------------------
But, I checked the following error:
--------------------------------------------------------------------------------------------
Error in routine card_hubbard (3):
Not allowed to specify two Hubbard channels that are the same for the same atom
--------------------------------------------------------------------------------------------
I've tried solving this in many ways, but I keep failing. I need the know-how of experienced people. Would you help me?
I am a beginner at Quantum Espresso, so I would like a detailed explanation if possible. Thank you.
P.S.: I attach input & output files.
QE has report your error, dear.
This part:
HUBBARD (ortho-atomic)
U Eu1-4f 6.0
J0 Eu2-4f 1.0
U Eu1-4f 6.0
Jo Eu2-4f 1.0
should be:
HUBBARD (ortho-atomic)
U Eu1-4f 6.0
J0 Eu1-4f 1.0
U Eu2-4f 6.0
J0 Eu2-4f 1.0
Thanks! I fixed it. Nevertheless, same problem happened.
I first tried assigning the Hubbard potential to only one element as follows:
-----------------------------------------------------------------------
HUBBARD (ortho-atomic)
U Eu1-4f 6.0
-----------------------------------------------------------------------
But at this time, the problem that Pseudopotential doesn't include 4f-shell information of Eu occured...
Do you know pseudopotential library that includes 4f-shell information of Eu atom?
I didn't find. Most libraries that I found only include 5s, 5p, 6s...(Eu's valence electron configuration: 5s25p64f76s2)..
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