[Pw_forum] Strange Lowdin Charges

[Wang Beizhou]

Dear all,

I encountered a problem when I calculated lowdin charges for MoS2 edge using projwfc.x of QE-5.4.0 . Part of the results was shown below:
-------------------------------------------------------------------
     Atom #  69: total charge =   5.7346, s =  1.5888, p =  4.1458, d =  0.0000,
     Atom #  70: total charge =   5.7839, s =  1.6118, p =  4.1721, d =  0.0000,
     Atom #  71: total charge =  14.2310, s =  2.3482, p =  6.8669, d =  5.0159,
     Atom #  72: total charge =  14.4296, s =  2.2972, p =  6.9909, d =  5.1415,
     Atom #  73: total charge =   5.8638, s =  1.6250, p =  4.2388, d =  0.0000,
     Atom #  74: total charge =   5.6876, s =  1.5856, p =  4.1019, d =  0.0000,
     Atom #  75: total charge =   5.6885, s =  1.5857, p =  4.1028, d =  0.0000,
     Atom #  76: total charge =  14.4255, s =  2.3021, p =  6.9983, d =  5.1251,
     Atom #  77: total charge =  14.3017, s =  2.3619, p =  6.9347, d =  5.0051,
------------------------------------------------------------------------
As you could see from the results above, the charges for Mo atom(#71) is 14-14.2310<0 while charges of S atom(#70) is 6- 5.7839>0. This is weird and abnormal. I have also tested MoS2 cluster and the results seemed to be reasonable. The input files for SCF and lowdin charges calculations were shown below:
------------------------------------------------
&CONTROL
  calculation='scf',
  restart_mode='from_scratch',
  nstep=55,
  iprint=10,
  etot_conv_thr=1.94d-04,
  forc_conv_thr=1.94d-03,
  pseudo_dir="/disk/rdisk09/upf_files",
  disk_io='low',
  wf_collect=.true.
  outdir='/disk/rdisk09/pw-wfc',
  prefix='pure',
  max_seconds=1700.0D5,
/

&SYSTEM
  ibrav=0,
  nat=96,
  ntyp=2,
!  nbnd=230,
  ecutwfc=30,
  ecutrho=240,
  nspin=1,
  input_dft='pbe',
  occupations='smearing',
  smearing='gaussian'
  degauss=2d-03,
/

&ELECTRONS
  conv_thr=1d-06,
  diago_david_ndim=6,
  mixing_mode='local-TF',
  mixing_ndim=20,
  mixing_beta=0.2d0,
  electron_maxstep=150,
/

&IONS
  ion_dynamics='bfgs',
  upscale=10.0,
!  trust_radius_ini=0.756d0,
!  trust_radius_min=0.378d0,
!  trust_radius_max=0.945d0,
/

ATOMIC_SPECIES
Mo   1.0  Mo.pbe-spn-rrkjus_psl.0.2.UPF
S    1.0  S.pbe-n-rrkjus_psl.0.1.UPF

CELL_PARAMETERS {bohr}
             37.03839294358365    0.00000000000000    0.00000000000000
              0.00000000000000   47.78739424883790    0.00000000000000
              0.00000000000000    0.00000000000000   22.03604620987204

ATOMIC_POSITIONS {bohr}
Mo      16.178904896   0.021011000  16.923677623
Mo      21.147881968   2.974967793  16.894101816
……
……
S       35.139272622  41.823716049  16.906787202
S       35.111475195  47.636308872  17.054520301

K_POINTS gamma
------------------------------------------------------------------------------
&PROJWFC
    outdir='/nfs/disk2/beizhwang3/software/pw-wfc'
    prefix='pure-0H'
    Emin=-20.0, Emax=20.0, DeltaE=0.01
    ngauss=0, degauss=0.002
/
-------------------------------------------------------------------------------
Any advice will be appreciated. Thanks for your kind attention!

Best,

Beizhou Wang
City University of Hong Kong
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