Spin Separated Calculations

BaderKit runs on whatever set of data is stored in the total property of the Grid class. By default, this data is read from the first set of data in a CHGCAR or cube format file. This typically represents the total charge density of both the spin-up and spin-down electrons.

In VASP, spin polarized calculations will also write an additional set of data representing the difference between the spin-up and spin-down charge densities. When read from file, this data is stored in the diff property of the Grid class.

Assuming we have run a spin-polarized calculation with VASP, we can run the Bader analysis on the separate spin-up and spin-down systems by creating two Grid and Bader class objects with the appropriate charge densities in the total property.

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Command LinePython

1. Split your file using the provided helper command. Replace 'chargefile' with your actual file path.

   baderkit split chargefile
   

2. Run the bader analysis on the spin up system and copy it to avoid overwriting.

   baderkit run chargefile_up
   mv bader_atom_summary.tsv bader_atom_summary_up.tsv
   mv bader_basin_summary.tsv bader_basin_summary_up.tsv
   

3. Run the bader analysis on the spin down system.

   baderkit run chargefile_down
   mv bader_atom_summary.tsv bader_atom_summary_down.tsv
   mv bader_basin_summary.tsv bader_basin_summary_down.tsv
   

# import 
from baderkit.core import Bader, Grid

# load the spin polarized charge grid. Make sure the `total_only` tag is set to
# false to indicate that we want to load all sets of data.
polarized_grid = Grid.from_vasp("CHGCAR", total_only=False)

# split the polarized grid to the spin up and spin down components
grid_up, grid_down = polarized_grid.split_to_spin()

# create our Bader classes
bader_up = Bader(grid_up)
bader_down = Bader(grid_down)

# get results
results_up = bader_up.results_summary
results_down = bader_down.results_summary

Tip

This analysis can be run on results from softwares other than VASP as well. Either set up the polarized_grid so that it follows VASP's total and diff format, or load/create the grid_up and grid_down from already split data.

Warning

This example does not use the core + valence charge density as we suggest in our warning. This is because VASP does not write spin separated AECCAR0 or AECCAR2 files. You can still use the CHGCAR_sum as a reference, but the bader basins will be defined by the total charge density, not the spin-polarized ones.