[QE-users] Magnetic force theorem in DFT+U formalism
Saritas, Kayahan
saritask at ornl.gov
Fri Nov 15 14:14:12 CET 2024
Hello Iurii,
Thanks for checking in with Luca, I appreciate it.
“As long as the ground state total energy is the same …“
I am guessing he meant that the ground state energy of collinear (with scalar rel. pp) (#1) should be equal to non-collinear (again with scalar rel.) (#2). We can hope that these two calculations can give the same total energy, but magnetic anisotropy energy can sometimes be on the order of micro eV, therefore in my opinion there can be some potential to bias the calculations following that route considering the very small energy scale.
“The first calculation can be carried out with scalar-relativistic pseudos, even if noncolin=.true. (and the flag nspin=2 should be avoided).”
I agree that the calculations will “run” following this route, but it would need to be tested (maybe at the limit of very small u to approach PBE) to see if the results make sense.
Best,
Kayahan
From: Timrov Iurii <iurii.timrov at psi.ch>
Date: Friday, November 15, 2024 at 4:13 AM
To: users at lists.quantum-espresso.org <users at lists.quantum-espresso.org>, Saritas, Kayahan <saritask at ornl.gov>
Subject: [EXTERNAL] Re: Magnetic force theorem in DFT+U formalism
Dear Kayahan,
I discussed this issue with Luca Binci who worked on the noncollinear DFT+U and this is what he replied:
"As long as the ground state total energy is the same, running the first calculation with noncolin=.true. (and specifying angle(1) and angle(2)) should bypass the problem. The alternative would be modifying the code, but that requires more time. The first calculation can be carried out with scalar-relativistic pseudos, even if noncolin=.true. (and the flag nspin=2 should be avoided)."
Greetings,
Iurii
----------------------------------------------------------
Dr. Iurii TIMROV
Tenure-track scientist
Laboratory for Materials Simulations (LMS)
Paul Scherrer Institut (PSI)
CH-5232 Villigen, Switzerland
+41 56 310 62 14
https://www.psi.ch/en/lms/people/iurii-timrov<https://urldefense.us/v2/url?u=https-3A__www.psi.ch_en_lms_people_iurii-2Dtimrov&d=DwMFAg&c=v4IIwRuZAmwupIjowmMWUmLasxPEgYsgNI-O7C4ViYc&r=m4gnbzeZqDqKb9gUts2smy4wU3AKr019Jj7aBnXZaGk&m=2Cg3XKbv2mpIYFin5IEOzMwtA2PUxX3xkqi-7V5OtdLfzkrGCv1nq3VmpAAUcuG7&s=FylhNMbQHPSCPxrWpvUkZiTWDQXq1UU0RSylXvNkpYY&e=>
________________________________
From: users <users-bounces at lists.quantum-espresso.org> on behalf of Saritas, Kayahan via users <users at lists.quantum-espresso.org>
Sent: Wednesday, November 13, 2024 20:36
To: users at lists.quantum-espresso.org <users at lists.quantum-espresso.org>
Subject: [QE-users] Magnetic force theorem in DFT+U formalism
Dear QE users,
I am trying to run the Force theorem example (see [1] below for the link) with DFT+U. The original example is using PBE. The calculation procedure is the following:
1. Run collinear SCF calculation
2. Use SCF collinear calculation density and potentials to run NSCF SOC calculations with different magnetization angles and lforcet=True and use the energy differences
I used Re atom in vacuum to test the procedure and here are the inputs I use:
For step 1:
&CONTROL
calculation = 'scf'
outdir = 'pwscf_output'
prefix = 'pwscf'
pseudo_dir = './'
wf_collect = .true.
/
&SYSTEM
degauss = 0.001
ecutwfc = 100
ibrav = 0
input_dft = 'pbe'
nat = 1
nosym = .false.
nspin = 2
ntyp = 1
occupations = 'smearing'
smearing = 'gauss'
starting_magnetization(1) = 1
tot_charge = 2
/
&ELECTRONS
conv_thr = 1e-07
/
ATOMIC_SPECIES
Re 186.2 Re.pz-spn-rrkjus_psl.1.0.0.UPF
ATOMIC_POSITIONS bohr
Re -1.66168343 -0.00000189 0.00000756
K_POINTS automatic
1 1 1 0 0 0
CELL_PARAMETERS bohr
18.89726133 0.00000000 0.00000000
0.00000000 18.89726133 0.00000000
0.00000000 0.00000000 18.89726133
HUBBARD atomic
U Re-5d 4
Then for step 2, I copied the entire SCF calculation folder into another folder and modified the input file as the following:
&CONTROL
calculation = 'nscf'
outdir = 'pwscf_output'
prefix = 'pwscf'
pseudo_dir = './'
wf_collect = .true.
/
&SYSTEM
angle1(1) = 90
angle2(1) = 0
degauss = 0.001
ecutwfc = 100
ibrav = 0
input_dft = 'pbe'
lspinorb = .true.
lforcet = .true.
nat = 1
nbnd = 14
noncolin = .true.
nosym = .true.
ntyp = 1
occupations = 'smearing'
smearing = 'gauss'
starting_magnetization(1) = 1
tot_charge = 2
/
&ELECTRONS
conv_thr = 1e-07
/
ATOMIC_SPECIES
Re 186.2 Re.rel-pz-spn-rrkjus_psl.1.0.0.UPF
ATOMIC_POSITIONS bohr
Re -1.66168343 -0.00000189 0.00000756
K_POINTS automatic
1 1 1 0 0 0
CELL_PARAMETERS bohr
18.89726133 0.00000000 0.00000000
0.00000000 18.89726133 0.00000000
0.00000000 0.00000000 18.89726133
HUBBARD atomic
U Re-5d 4
Notice, that between step 1 and 2 parameters in the &CONTROL and &SYSTEM cards are different and step 1 uses a scalar relativistic potential, while step 2 uses full relativistic potential from pslibrary.
Step 1 completes successfully, but the step 2 gives the following error:
Error in routine read_scf (1):
Reading ldaU ns
I used QE 7.4 to run these calculations. Both step 1 and step 2 are completed without any error if I use PBE only (no hubbard-U).
I am suspecting that the error is because in the NSCF-SOC calculation expects a Hubbard calculation manifold double in size (10x10 in noncollinear vs 5x5 in collinear in d-orbitals).
I am not sure if there are any fundamental reasons why the force theorem would not work in DFT+U formalism, because the above examples work when Hubbard-U is disabled (PBE only).
[1] https://gitlab.com/QEF/q-e/-/blob/f184591e9f34cfcc7767505a23977a92286e8ba6/PP/examples/ForceTheorem_example/run_example<https://urldefense.us/v2/url?u=https-3A__gitlab.com_QEF_q-2De_-2D_blob_f184591e9f34cfcc7767505a23977a92286e8ba6_PP_examples_ForceTheorem-5Fexample_run-5Fexample&d=DwMFAg&c=v4IIwRuZAmwupIjowmMWUmLasxPEgYsgNI-O7C4ViYc&r=m4gnbzeZqDqKb9gUts2smy4wU3AKr019Jj7aBnXZaGk&m=2Cg3XKbv2mpIYFin5IEOzMwtA2PUxX3xkqi-7V5OtdLfzkrGCv1nq3VmpAAUcuG7&s=2z-aed_dR5xWLrtTaJvSl2HABwNNihVi2QfCpTWM-7s&e=>
Best,
Kayahan
Dr. Kayahan Saritas
R&D Associate, Materials Theory Group
Materials Sciences and Technology Division
Oak Ridge National Laboratory
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