[Pw_forum] A question on atomic magnetic moments

[Srijan Kumar Saha]

 Dear QE users,

 QE is able to find the correct symmetry for the input file, added at the
end of this email.
 Here is the proof:
 48 Sym.Ops. (with inversion).

 However, during vc-relax it breaks the symmetry.
 Proof goes here:
   0.000000000   0.000000000   0.000000000
   0.250189867   0.250189867   0.250189867
   0.000000000   0.250189689   0.250189689
   0.250189689   0.000000000   0.250189689
   0.250189689   0.250189689   0.000000000
   0.500379494   0.000000000   0.000000000
   0.750569121   0.250189867   0.250189867
   0.500379494   0.250189728   0.250189728
   0.750569299   0.000000000   0.250189689
   0.750569299   0.250189689   0.000000000
   0.000000000   0.500379494   0.000000000
   0.250189867   0.750569121   0.250189867
   0.000000000   0.750569299   0.250189689
   0.250189728   0.500379494   0.250189728
   0.250189689   0.750569299   0.000000000
   0.500379494   0.500379494   0.000000000
   0.750569121   0.750569121   0.250189867
   0.500379494   0.750569260   0.250189728
   0.750569260   0.500379494   0.250189728
   0.750569299   0.750569299   0.000000000
   0.000000000   0.000000000   0.500379494
   0.250189867   0.250189867   0.750569121
   0.000000000   0.250189689   0.750569299
   0.250189689   0.000000000   0.750569299
   0.250189728   0.250189728   0.500379494
   0.500379494   0.000000000   0.500379494
   0.750569121   0.250189867   0.750569121
   0.500379494   0.250189728   0.750569260
   0.750569299   0.000000000   0.750569299
   0.750569260   0.250189728   0.500379494
   0.000000000   0.500379494   0.500379494
   0.250189867   0.750569121   0.750569121
   0.000000000   0.750569299   0.750569299
   0.250189728   0.500379494   0.750569260
   0.250189728   0.750569260   0.500379494
   0.500379494   0.500379494   0.500379494
   0.750569121   0.750569121   0.750569121
   0.500379494   0.750569260   0.750569260
   0.750569260   0.500379494   0.750569260
   0.750569260   0.750569260   0.500379494


  Is this possible to keep symmetry of the initial system conserved during
vc-relax with BFGS ?

  Input file:
    &control
    calculation='vc-relax'
    restart_mode='from_scratch',
    prefix='pbmno',
    tstress = .true.
    tprnfor = .true.
    wf_collect=.true.
    verbosity='high'
    etot_conv_thr=1.0D-5,
    forc_conv_thr=1.0D-4,
 /
  &system
    ibrav =  1,
    nat = 40,
    ntyp=3,
    celldm(1)=20.70
    nosym=.FALSE.
    ecutwfc = 30.0,
        ecutrho = 240.0,
    occupations='smearing',
    smearing='fd',
    degauss=0.005d0,
    nspin=2
      starting_magnetization(2)=1.0,
 /
 &electrons
    diagonalization = 'david'
    conv_thr =  1.0d-9
    mixing_beta = 0.7
 /
 &ions
 /
 &cell
 /
ATOMIC_SPECIES
 Pb   1.0        Pb.UPF
 Mn   1.0       Mn.UPF
 O     1.0       O.UPF
ATOMIC_POSITIONS (alat)
Pb         0.00  0.00  0.00
Mn         0.25  0.25  0.25
O          0.00  0.25  0.25
O          0.25  0.00  0.25
O          0.25  0.25  0.00
Pb          0.50  0.00  0.00
Mn          0.75  0.25  0.25
O         0.50  0.25  0.25
O          0.75  0.00  0.25
O          0.75  0.25  0.00
Pb          0.00  0.50  0.00
Mn          0.25  0.75  0.25
O         0.00  0.75  0.25
O          0.25  0.50  0.25
O          0.25  0.75  0.00
Pb          0.50  0.50  0.00
Mn          0.75  0.75  0.25
O         0.50  0.75  0.25
O          0.75  0.50  0.25
O          0.75  0.75  0.00
Pb          0.00  0.00  0.50
Mn          0.25  0.25  0.75
O         0.00  0.25  0.75
O          0.25  0.00  0.75
O          0.25  0.25  0.50
Pb          0.50  0.00  0.50
Mn          0.75  0.25  0.75
O         0.50  0.25  0.75
O          0.75  0.00  0.75
O          0.75  0.25  0.50
Pb          0.00  0.50  0.50
Mn          0.25  0.75  0.75
O         0.00  0.75  0.75
O          0.25  0.50  0.75
O          0.25  0.75  0.50
Pb          0.50  0.50  0.50
Mn          0.75  0.75  0.75
O         0.50  0.75  0.75
O          0.75  0.50  0.75
O          0.75  0.75  0.50
K_POINTS {automatic}
 2 2 2  0 0 0

Thanking you and with my best regards,
Srijan K
CCMT
Indian Institute of Science
India 560012
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