[QE-users] Query for skip_type and equiv_type for DFT+U+V

Iurii TIMROV iurii.timrov at epfl.ch
Wed Nov 24 15:41:01 CET 2021


Ok, so you have this:


atom    1   Tr[ns(na)]=   6.2349321 -> Fe1
atom    2   Tr[ns(na)]=   6.2349321 -> Fe1
atom    3   Tr[ns(na)]=   6.2349321 -> Fe1
atom    4   Tr[ns(na)]=   6.2348428 -> Fe1
atom    5   Tr[ns(na)]=   6.1942515 -> Fe2
atom    6   Tr[ns(na)]=   6.1942515 -> Fe2


Just use find_atpert=1 and docc_thr=1.d-4. This will perturb one Fe1 atom and one Fe2 atom, because they have different occupations. If you want to have the same U for both Fe1 and Fe2 then set  docc_thr=5.d-2: in this case the code will perturb only Fe1 atom.


HTH


Iurii


--
Dr. Iurii TIMROV
Senior Research Scientist
Theory and Simulation of Materials (THEOS)
Swiss Federal Institute of Technology Lausanne (EPFL)
CH-1015 Lausanne, Switzerland
+41 21 69 34 881
http://people.epfl.ch/265334
________________________________
From: users <users-bounces at lists.quantum-espresso.org> on behalf of Dr. K. C. Bhamu <kcbhamu85 at gmail.com>
Sent: Wednesday, November 24, 2021 3:31:30 PM
To: Quantum ESPRESSO users Forum
Subject: Re: [QE-users] Query for skip_type and equiv_type for DFT+U+V

Thanks  Iurii,
I find that "find_atpert" is by default set at 1.
With the setting mention in my previous mail, I got the below error:
 Error in routine hp_find_inequiv_sites (1):
     skip_type must not be setup from the input when find_atpert=1.
For magnetite structure (Fe3O4), Fe has two states: Fe2+ and Fe3+.

 Here is the Tr[ns(na)] and input file
atom    1   Tr[ns(na)]=   6.2349321
atom    1   Mag[ns(na)]=   3.5251042
atom    2   Tr[ns(na)]=   6.2349321
atom    2   Mag[ns(na)]=   3.5251042
atom    3   Tr[ns(na)]=   6.2349321
atom    3   Mag[ns(na)]=   3.5251042
atom    4   Tr[ns(na)]=   6.2348428
atom    4   Mag[ns(na)]=   3.5251547
atom    5   Tr[ns(na)]=   6.1942515
atom    5   Mag[ns(na)]=  -3.5314272
atom    6   Tr[ns(na)]=   6.1942515
atom    6   Mag[ns(na)]=  -3.5314272
atom    7   Tr[ns(na)]=   5.0802986
atom    7   Mag[ns(na)]=   0.0754368
atom    8   Tr[ns(na)]=   5.0802986
atom    8   Mag[ns(na)]=   0.0754368
atom    9   Tr[ns(na)]=   5.0802986
atom    9   Mag[ns(na)]=   0.0754368
atom   10   Tr[ns(na)]=   5.0802986
atom   10   Mag[ns(na)]=   0.0754368
atom   11   Tr[ns(na)]=   5.0802986
atom   11   Mag[ns(na)]=   0.0754368
atom   12   Tr[ns(na)]=   5.0802986
atom   12   Mag[ns(na)]=   0.0754368
atom   13   Tr[ns(na)]=   5.0802792
atom   13   Mag[ns(na)]=   0.0754401
atom   14   Tr[ns(na)]=   5.0802792
atom   14   Mag[ns(na)]=   0.0754401

Input file:

&CONTROL
  calculation = 'vc-relax'
  restart_mode='from_scratch',
  etot_conv_thr =   0.0001
  forc_conv_thr =   0.001
  outdir = './temp/'
  prefix = 'pwscf'
  pseudo_dir = '~/PP/'
  tprnfor = .true.
  tstress = .true.
  verbosity = 'high'
/
&SYSTEM
  degauss =   0.022
  ecutrho =   320
  ecutwfc =   40
  occupations = 'smearing' ,    smearing = 'mp'
  ibrav = 0
  nat = 14
  nosym = .false.
  ntyp = 3
nspin=2
  starting_magnetization(1) =   0.8
  starting_magnetization(2) =   -0.8
  starting_magnetization(3) =   0.0

  lda_plus_u = .true.,
  lda_plus_u_kind = 2,
  U_projection_type = 'ortho-atomic',
  Hubbard_V(1,1,1) = 1.d-8
  Hubbard_V(5,5,1) = 1.d-8
  Hubbard_V(7,7,1) = 1.d-8
!Hubbard_parameters = 'file'


/
&ELECTRONS
  conv_thr =   1.0000000000d-06
  electron_maxstep = 400
  mixing_beta =   1.5000000000d-01
/
&IONS
                ion_dynamics = 'bfgs'
 /
&CELL
/

ATOMIC_SPECIES
Fe1     55.845 Fe.pbe-nd-rrkjus.UPF
Fe2     55.845 Fe.pbe-nd-rrkjus.UPF
O      15.9994 O.pbe-rrkjus.UPF
ATOMIC_POSITIONS (crystal)
Fe1           0.0000000000       -0.0000000000       -0.0000000000
Fe1           0.5000000000        0.0000000000        0.0000000000
Fe1           0.9999999892        0.5000000216       -0.0000000000
Fe1           0.9999999965        0.9999999956        0.5000000115
Fe2           0.3749993721        0.3749993349        0.3750019210
Fe2           0.6250006225        0.6250006532        0.6249981020
O             0.2454868415        0.2454868399        0.2454949640
O             0.7545131845        0.7545131098        0.7545050345
O             0.7635313546        0.2454868399        0.2454949640
O             0.2364686713        0.7545131098        0.7545050345
O             0.2454868307        0.7635313746        0.2454949640
O             0.7545132523        0.2364686217        0.7545050345
O             0.2454908593        0.2454908222        0.7635274591
O             0.7545090629        0.7545091741        0.2364725394

CELL_PARAMETERS (angstrom)
   5.944682649   0.000000000   0.000000000
   2.972341325   5.148246192   0.000000000
   2.972341325   1.716082064   4.853885701

K_POINTS automatic
7 7 7 0 0 0

Regards
Bhamu




> As all Fe will have the same Hubbard parameter (as reported in the literature for the same system)...


In the literature people often use empirical U, so that's why they use a single value of U for all Fe atoms. With the HP code you can do things better, i.e. to find out if there are non-equivalent Fe atoms that require their own first-principles U.


HTH


Iurii


P.S.: "Dr." is used with the last name not with the first name, so in my case this will be "Dear Dr. Timrov". But if you want to address me using my first name then just write "Dear Iurii". Sorry, I don't want to bother you with this, but just to makes things clear 😊


--
Dr. Iurii TIMROV
Senior Research Scientist
Theory and Simulation of Materials (THEOS)
Swiss Federal Institute of Technology Lausanne (EPFL)
CH-1015 Lausanne, Switzerland
+41 21 69 34 881
http://people.epfl.ch/265334
________________________________
From: users <users-bounces at lists.quantum-espresso.org<mailto:users-bounces at lists.quantum-espresso.org>> on behalf of Dr. K. C. Bhamu <kcbhamu85 at gmail.com<mailto:kcbhamu85 at gmail.com>>
Sent: Wednesday, November 24, 2021 1:00:13 PM
To: Quantum Espresso users Forum
Subject: [QE-users] Query for skip_type and equiv_type for DFT+U+V

Dear Dr. Iurii (😊),

The ATOMIC_POSITIONS cart of my structure (ferrimagnetic system with ntyp = 3 ) is

ATOMIC_POSITIONS (crystal)
Fe1           0.0000000000       -0.0000000000       -0.0000000000 (four times)
Fe2           0.3749993721        0.3749993349        0.3750019210 (two times)
O             0.2454868415        0.2454868399        0.2454949640 (eight times)

Previously, based on ATOMIC_SPECIES cart, I defined my Hubbard tag as below

  Hubbard_V(1,1,1) = 1.d-8
  Hubbard_V(2,2,1) = 1.d-8
  Hubbard_V(3,3,1) = 1.d-8

In the hp output file, I saw that only one  Fe1 atom was perturbed.

Then I defined below Hubbard tags according to ATOMIC_POSITIONS cart as

  Hubbard_V(1,1,1) = 1.d-8
  Hubbard_V(5,5,1) = 1.d-8
  Hubbard_V(7,7,1) = 1.d-8

which perturbed four atoms

        1      Fe1    55.8450   tau( 1) = (  0.00000  0.00000  0.00000  )
        4      Fe1    55.8450   tau( 4) = (  1.75000  1.01036  0.40825  )
        5      Fe2    55.8450   tau( 5) = (  0.75000  0.43301  0.30619  )
        7      O      15.9994   tau( 7) = (  0.49098  0.28347  0.20045  )

As all Fe will have the same Hubbard parameter (as reported in the literature for the same system), I would like to skip the perturbation for atom Fe1(4) and Fe2(5).

Is it okay if I do so?

To skip the perturbation for Fe1(4) and Fe2(5), I have updated below tags in my hp input file:

skip_type(1)=.true.
skip_type(2)=.true.
equiv_type(1)=1
equiv_type(2)=1
disable_type_analysis=.true.,

Could you please correct me if this modification is correct or not?

Sorry for the list of questions. But I am sure, my these queries will be helpful for others too.

Thanks and regards

K C Bhamu

Postdoctoral Fellow
University of Ulsan
South Korea

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