[QE-users] non-convergency of DFPT+U calculation

[Merlin Meheut]

Dear PWSCF users,

I am trying to realize a phonon calculation (at gamma) with +U on fayalite
(olivine structure Fe2SiO4) with anti-ferromagnetic configuration , and
whether the calculation goes fine without +U, I have one representation
(#23) that systematically fails to converge when I add a +U. I tried
several values for the +U (0.5, 2.5, 4), several functionals (PZ, PBE), but
the result is always the same. I have used QE versions 6.4 and 6.4.1 on two
different computing centers . Would you have any idea about the reasons for
such a failure? I am specifically worried by one output message: "Atomic
wfc used for the DFT+U projector are NOT orthogonalized", but I don't know
how to fix that.

Here are examples of my scf and ph inputs, and the failing ph output:

scf:
 &control
       calculation = 'scf',
    (...)
    tprnfor        = .true.,
    tstress        = .true.,
/&end
&system
    ibrav =0, celldm(1)=9.107535,
    nat =28, ntyp = 4, ecutwfc =80.0, ecutrho = 320.0,
    nspin=2,   tot_magnetization=0,
    starting_magnetization(1)=0.5, starting_magnetization(2)=-0.5,
     lda_plus_u = .true., U_projection_type = 'atomic',
      Hubbard_U(1)=2.4, Hubbard_U(2)=2.6
/&end
 &electrons
   electron_maxstep = 150,
          conv_thr = 1.d-11,
       mixing_mode = 'plain',
       startingwfc = 'atomic',
       mixing_beta = 0.3,
/&end
ATOMIC_SPECIES
  Fe1  55.9349  Fe.pz-n-rrkjus_psl.1.0.0.UPF
  Fe2  55.9349   Fe.pz-n-rrkjus_psl.1.0.0.UPF
  Si   27.9769  Si.pz2.UPF
  O    15.9949   O.pz.UPF
(...)

ph input:
 &inputph
   amass(1)=55.9349,
   amass(2)=55.9349,
   amass(3)=27.9769,
   amass(4)=15.9949,
   alpha_mix(1) = 0.5,
   ! ldisp=.true., nq1=2, nq2=2, nq3=2,
   tr2_ph =  1.0D-17,
   prefix='FAYA2',
   fildyn='mat.$PREFIX',
   lraman=.false.,
   epsil =.false.,
   trans =.true.,
   zue = .false.,
   zeu= .false.,
   start_irr=23,
   last_irr=23,
   outdir         ='./',
/&end
0.0 0.0 0.0

ph output:
 Representation # 23 mode #  23

     Self-consistent Calculation

      iter #   1 total cpu time :    58.7 secs   av.it.:   8.5
      thresh= 1.000E-02 alpha_mix =  0.500 |ddv_scf|^2 =  1.045E-06

      iter #   2 total cpu time :    62.9 secs   av.it.:  23.0
      thresh= 1.022E-04 alpha_mix =  0.500 |ddv_scf|^2 =  2.668E-04

      iter #   3 total cpu time :    66.4 secs   av.it.:  17.5
      thresh= 1.633E-03 alpha_mix =  0.500 |ddv_scf|^2 =  3.033E-03

      iter #   4 total cpu time :    69.0 secs   av.it.:  11.0
      thresh= 5.508E-03 alpha_mix =  0.500 |ddv_scf|^2 =  5.602E-02

      iter #   5 total cpu time :    73.0 secs   av.it.:  15.5
      thresh= 1.000E-02 alpha_mix =  0.500 |ddv_scf|^2 =  1.238E+00

      iter #   6 total cpu time :    76.7 secs   av.it.:  19.5
      thresh= 1.000E-02 alpha_mix =  0.500 |ddv_scf|^2 =  2.841E+01

      iter #   7 total cpu time :    80.9 secs   av.it.:  23.0
      thresh= 1.000E-02 alpha_mix =  0.500 |ddv_scf|^2 =  6.534E+02

      iter #   8 total cpu time :    85.3 secs   av.it.:  24.5
      thresh= 1.000E-02 alpha_mix =  0.500 |ddv_scf|^2 =  1.446E+04

      iter #   9 total cpu time :    90.1 secs   av.it.:  27.5
      thresh= 1.000E-02 alpha_mix =  0.500 |ddv_scf|^2 =  3.214E+05

      iter #  10 total cpu time :    95.5 secs   av.it.:  30.0
      thresh= 1.000E-02 alpha_mix =  0.500 |ddv_scf|^2 =  7.200E+06

(.....)

Thank you in advance for your help! Feel free to ask for any further
calculation details.

Regards,
-- 
Merlin Méheut
adresse labo:
GET - OMP   - Université Paul Sabatier
14 avenue Edouard Belin
31400 Toulouse
FRANCE
tel: (+33) 5 61 33 26 17
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