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
Best,
Kayahan
Dr. Kayahan Saritas
R&D Associate, Materials Theory Group
Materials Sciences and Technology Division
Oak Ridge National Laboratory
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