[QE-users] Problems related to Hubbard potential when vc-relax is calculated

[임용식]

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:

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&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





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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



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Q1) Please let me know how to solve this problem.



Morever, The orbital shell of Eu atom used to Hubbard energy is 4f(since Eu orbital valency configuration: 5s2 5p6 4f7 6s2). My pseudopotential of Eu only has 5s, 5p & 6s. So. following error occurs:



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Error in routine offset_atom_wfc (1):

Mismatch between the requested and available manifolds







using ibrav=0 with symmetry is DISCOURAGED, use correct ibrav instead

Eu pseudopotential contains the orbitals: 5S 6S 5P 6P 5D

Requested Hubbard manifold from the input: 4F



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Q2) Can I know the psudopotential library or source including 4f-orbital of Eu atom? I couldn't find that.





Because I beginner at Quantum Espressso, so I would appreciate it if you could explain it in as much detail as possible!!



Thank you.


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