[QE-developers] Issue applying multiple Hubbard Us to same atom [QE 7-1]

[William Hewett]

Hi QE Devs,

I'm trying to apply two Hubbard U terms to one atom using QE 7-1. I've done
this successfully in previous versions of QE by making some changes to the
code (set_hubbard_l.src etc.) before compiling and using the commands:

Hubbard_U(n) = x1
Hubbard_U_back(n) = x2

In QE 7-1 I think this should not be required with the new HUBBARD card in
the input file. However, when applying multiple Us to one atom it seems the
first orbital is hit twice. Using this HUBBARD card in the input file:

HUBBARD (atomic)

U Gd-5D 8.4

U Gd-4F 5.0

I can see in the output file that both the Us are being applied to the 5D
channel.

Hubbard projectors: atomic

Hubbard parameters of DFT+U (Dudarev formulation) in eV:

U(Gd-5d) =  8.4000

U2(Gd-5d) =  5.0000


Swapping the order in the HUBBARD card, i.e. 4F first, will cause the 4F
orbital to be hit twice.

I can also check that this is not an issue with the labeling in the PP i.e.

 <PP_CHI.1 type="real" size="  1110" l="0" occupation=" 2.0000" columns="3"
*label*="5S">

 <PP_CHI.2 type="real" size="  1110" l="0" occupation=" 2.0000" columns="3"
*label*="6S">

 <PP_CHI.3 type="real" size="  1110" l="1" occupation=" 6.0000" columns="3"
*label*="5P">

 <PP_CHI.4 type="real" size="  1110" l="1" occupation=" 0.0000" columns="3"
*label*="6P">

 <PP_CHI.5 type="real" size="  1110" l="2" occupation=" 1.0000" columns="3"
*label*="5D">

 <PP_CHI.6 type="real" size="  1110" l="2" occupation=" 0.0000" columns="3"
*label*="6D">

 <PP_CHI.7 type="real" size="  1110" l="3" occupation=" 7.0000" columns="3"
*label*="4F">

 <PP_CHI.8 type="real" size="  1110" l="3" occupation=" 0.0000" columns="3"
*label*="5F">


All looks ok. Note that I've manually added the labels to this (Gd) PP, but
the behaviour is reproducible with other PPs too.

I think this is not the intended behavior of the code?

Here is the full input file:

&CONTROL

  calculation = 'scf'

  verbosity = 'high'

  restart_mode = 'from_scratch'

  outdir = './output/'

  prefix = 'GdN'

  pseudo_dir = './'


/

&SYSTEM

  ecutrho =   200

  ecutwfc =   50

  ibrav = 2

  A = 4.999

  nat = 2

  nspin = 2

  ntyp = 2

  nbnd = 16

  occupations = 'smearing'

  degauss =   1.0d-02

  smearing='gauss'

  starting_magnetization(1) =   1.0

  starting_magnetization(2) =   0.0

/


&ELECTRONS

  conv_thr =   1.0d-06

/

&IONS

/

&CELL

/


ATOMIC_SPECIES

Gd     157.25 Gd.GGA-PBE-paw-v1.0.UPF

N      14.0067 N.pbe-kjpaw.UPF


ATOMIC_POSITIONS {crystal}

Gd           0.0000000000       0.0000000000       0.0000000000

N            0.5000000000       0.5000000000       0.5000000000


K_POINTS automatic

6 6 6 0 0 0


HUBBARD (atomic)

U Gd-5D 8.4

U Gd-4F 5.0

Kind regards,

William Hewett
Postdoctoral Researcher
Victoria University of Wellington
New Zealand
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