Details of spin polarization


#1

I have a question about the way in which spin-polarization is handled in the MP calculations. I see on the Wiki that “All computations are performed with spin polarization on and with magnetic ions in a high-spin ferromagnetic initialization”. Can you please clarify what this specifically means (i.e. what magnetic moments are initialized)? For instance, are only d- and f-block transition elements initialized with high-spin (as discussed in the Jain et al. paper), or is it truly all calculations? In addition, what exactly does “high-spin” correspond to?Thank you for clarifying this.


#2

Hi arosen,

All calculations are performed with spin-polarization on, and we use a specific value for the initial magnetic moments supplied to VASP for each element that’s ~2-3 higher than what we typically encounter in the calculated ground-state magnetic configuration for those elements. Those are shown here: https://github.com/materialsproject/pymatgen/blob/master/pymatgen/io/vasp/VASPIncarBase.yaml. Everything without a value specified directly in the VASP input set is initialized to 0.6.

More broadly, if you’re interested in any of the parameters we use for a given calculations, you should be able to see a set of VASP input files corresponding to a given structure using the following snippet. Note that you’ll need to set your PMG_VASP_PSP_DIR variable in .pmgrc.yaml for output to write.

from pymatgen.io.vasp.sets import MPRelaxSet
from pymatgen import MPRester
mpr = MPRester(YOUR_API_KEY_HERE)

structure = mpr.get_structure_by_material_id(MATERIAL_ID_HERE)

vasp_input_set = MPRelaxSet(structure)
vasp_input_set.write_input('.')