Spin with Siesta
From version 2.31 of c2x, the Siesta support is sufficient for the following example.
SystemLabel FeO SaveRho .true. LatticeConstant 1.0 Ang %block LatticeVectors 0.000000 4.332000 4.332000 2.166000 0.000000 2.166000 2.166000 2.166000 0.000000 %endblock LatticeVectors NumberOfAtoms 4 NumberOfSpecies 2 %block ChemicalSpeciesLabel 1 8 O 2 26 Fe %endblock ChemicalSpeciesLabel AtomicCoordinatesFormat Fractional %block AtomicCoordinatesAndAtomicSpecies 0.250000 0.500000 0.500000 1 0.750000 0.500000 0.500000 1 0.000000 0.000000 0.000000 2 0.500000 0.000000 0.000000 2 %endblock AtomicCoordinatesAndAtomicSpecies SpinPolarized .true. %block DMInitSpin 3 2.000000 4 -2.000000 %endblock DMInitSpin MeshCutoff 200 Ry %block kgrid_Monkhorst_Pack 2 0 0 0.500000 0 3 0 0.000000 0 0 3 0.000000 %endblock kgrid_Monkhorst_Pack
One can then needs to supply suitable pseudopotentials. Both
O.psf can be found amongst the
examples distributed with Siesta. With these in the current
directory along with the above .fdf file, one can run Siesta as
$ siesta < FeO.fdf > FeO.out
Now one can analyse and visualise the results. In this case we choose to expand the system back to a cubic cell. Note that Siesta's .RHO file does not contain atomic positions, so c2x also reads the corresponding .XV file.
$ c2x -csv -X='(8.664,0,0)(0,8.664,0)(0,0,8.664)' FeO.RHO FeO.xsf Grid size 48x24x24 spins=2 Recorded data are single precision Attempting to read FeO.XV Also reading FeO.XV Cell volume 40.647690 natoms 4 Spin components (density): 2 Spin components (bands): 1 First FFT grid 48 24 24 spins=2 spinors=1 Found 3D data for Density min=0.0020457 max=6.86912 sum=19045.3 int=28.0001 (integral is e per cell for charge and spin densities) Found 3D data for Spin min=-3.94505 max=3.94505 sum=6.4837e-14 int=9.53225e-17 int|s|=7.06093 (integral is e per cell for charge and spin densities) New cell volume 650.362259 (16 times old) New FFT grid is 72 72 72 New FFT grid is 72 72 72
The integrated charge of 28 is consistent with the pseudopotentials used (+6 for O, +8 for Fe, two of each). The spin data is almost perfectly antiferromagnetic, and the value of int|s| implies a magnetic moment per Fe atom of 3.53μB, which is consistent with the literature and the other calulations here.
As the resulting picture is indistinguishable from the one produced by QE, that image is repeated below: