[Pw_forum] problem: mix non-relativistic pp with fully-relativistic pp when turning on spin-orbit

[Jiawei Zhou]

Dear all,

I want to calculate the band structure of MnTe above the Neel 
temperature (which is around room temperature and is a paramagnetic 
phase). Originally I wanted to include spin-orbit coupling because Te is 
a heavy element. So I used pslibrary to generate rel-pz-n-nc type 
fully-relativistic pseudopotential. But when I calculated the band using 
'bands' option it gives me errors:

Error in routine cdiaghg (262):
S matrix not positive definite.

I searched the forum and found suggestions to change pseudopotential. 
But the thing is I don't want to exclude spin-orbit coupling for element 
Te. So I tried mixing non relativistic Mn pp with fully relativistic Te 
pp and still turned on spin-orbit calculation. The calculation goes on 
well. But I don't know how the spin-orbit calculations are done in the 
pw. I wonder in this case how the material is modeled? (only Te includes 
spin-orbit coupling because its pseudopotential is in fully-relativistic 
form?) Thanks a lot.


script is shown below:

  &control
    calculation = 'scf'
    wf_collect=.true.
    restart_mode='from_scratch'
    prefix='MnTe-scf'
    tstress = .true.
    tprnfor = .true.
    pseudo_dir = '$PSEUDO_DIR'
    outdir = '$OUTDIR'
/
  &system
    ibrav=0, celldm(1)=7.8
    nat= 4, ntyp= 2,
    ecutwfc =60  , occupations='smearing', degauss=0.005, smearing='mv',
    lspinorb=.true.,
    noncolin=.true.,
    starting_magnetization(1)=0.0
    starting_magnetization(2)=0.0
/
  &electrons
    diagonalization='david'
    mixing_mode = 'plain'
    mixing_beta = 0.7
    conv_thr = 1.0d-12
/
ATOMIC_SPECIES
  Mn 54.938 Mn.pz-sp-hgh.UPF
  Te 127.60 Te.rel-pz-n-nc.0.3.1.UPF
ATOMIC_POSITIONS (alat)
  Mn       0.000000000  -0.000000000   0.000000000
  Te      -0.000000000   0.568151165   0.294296057
  Mn      -0.000000000  -0.000000000   0.588590750
  Te       0.492033342   0.284075582   0.882885442
K_POINTS { automatic }
  20 20 12 1 1 1
CELL_PARAMETERS
    0.984066685  -0.000000000   0.000000000
   -0.492033342   0.852226749   0.000000000
    0.000000000  -0.000000000   1.177181498

Best,
Jiawei