[Pw_forum] Occupation number

[Peng Chen]

Hi All,

When I tried to do GGA/GGA+U computation on Ni3V2O8, the occupation number
of Ni looks a little weird. In this compound,  d orbitals of Ni  split into
t2g (dxy, dxz,dyz) and eg (dx^2-y^2, dz^2) because of NiO6 octahedral
coordination. So the down spin will occupy t2g states. But both GGA and
GGA+U results show the occupation of dxz, dyz and dx^2-y^2. I tried to
write occupation matrix using  starting_ns_eigenvalue so that the
occupation can be dxy, dxz and dyz, but the scf calculation can not reach
convergence. Any suggestion is appreciated!


GGA after the first iteration:
    eigenvalues:
  0.059  0.066  0.075  0.146  0.161
    eigenvectors:
  0.009  0.001  0.000  0.000  0.990
  0.000  0.000  0.997  0.003  0.000
  0.076  0.924  0.000  0.000  0.000
  0.916  0.075  0.000  0.000  0.009
  0.000  0.000  0.003  0.997  0.000
    occupations:
  0.160  0.001  0.000 -0.010  0.000
  0.001  0.075  0.000  0.000 -0.004
  0.000  0.000  0.066 -0.002  0.001
 -0.010  0.000 -0.002  0.060  0.000
  0.000 -0.004  0.001  0.000  0.146

GGA after scf convergence:
    eigenvalues:
  0.336  0.364  0.987  0.988  0.991
    eigenvectors:
  0.030  0.968  0.002  0.000  0.000
  0.001  0.000  0.026  0.822  0.151
  0.000  0.000  0.063  0.175  0.761
  0.000  0.001  0.909  0.002  0.088
  0.968  0.030  0.000  0.001  0.000
    occupations:
  0.364 -0.003 -0.014  0.022  0.005
 -0.003  0.988 -0.001  0.000 -0.024
 -0.014 -0.001  0.990  0.001  0.001
  0.022  0.000  0.001  0.987 -0.001
  0.005 -0.024  0.001 -0.001  0.338


GGA+U after the first iteration:
   eigenvalues:
  0.071  0.079  0.095  0.157  0.172
    eigenvectors:
  0.008  0.000  0.000  0.000  0.992
  0.024  0.363  0.607  0.006  0.000
  0.000  0.630  0.369  0.001  0.000
  0.967  0.006  0.018  0.000  0.008
  0.000  0.000  0.006  0.993  0.000
    occupations:
  0.171  0.001  0.001 -0.009  0.000
  0.001  0.089 -0.008 -0.003 -0.005
  0.001 -0.008  0.085  0.001  0.002
 -0.009 -0.003  0.001  0.072  0.000
  0.000 -0.005  0.002  0.000  0.157

GGA+U after scf convergence:
    eigenvalues:
  0.265  0.306  0.995  0.996  0.996
    eigenvectors:
  0.010  0.988  0.001  0.000  0.000
  0.001  0.000  0.003  0.919  0.077
  0.000  0.000  0.098  0.060  0.841
  0.000  0.001  0.897  0.020  0.082
  0.989  0.010  0.000  0.001  0.000
    occupations:
  0.307 -0.002 -0.014  0.023  0.004
 -0.002  0.995  0.000  0.000 -0.024
 -0.014  0.000  0.996  0.001  0.000
  0.023  0.000  0.001  0.994 -0.001
  0.004 -0.024  0.000 -0.001  0.266


-- 
  Best Regards.
        Peng
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