[Pw_forum] Occupation number

[Stefano de Gironcoli]

are you sure the code is not correct?
how are the oxygen octahedra oriented  in your case?
a rotation of pi/4 around z would do..
stefano

On 09/09/2012 04:35 AM, Peng Chen wrote:
> 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
>
>
>
>
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