zfs keywords

Zero-field splitting calculator

zfs.correction

Spin-contamination correction of D. A Kohn-Sham determinant with spin polarization is not a pure spin state, and part of the dipolar interaction it gives is spurious (the spin contamination; its size is printed as <S^2> - S(S+1)). ‘frozen’ applies the correction of Biktagirov, Schmidt and Gerstmann, Phys. Rev. Research 2, 022024 (2020), Eq. 4, with the M_S = S-1 determinants built from the orbitals of the ground state; the uncorrected value is printed as well. ‘none’ computes the uncorrected D only, the quantity usually reported in plane-wave calculations.

type: string

default: 'frozen'

allowed: 'frozen','none'

example: zfs.correction = 'frozen'

zfs.axis

Cartesian direction along which D = 3/2 D_zz is reported, e.g. the symmetry axis of the defect. If empty, the principal axis of the tensor (largest eigenvalue in absolute value) is used. Along a threefold axis the value is the average over the threefold rotations.

type: array

size: [1,3]

example: zfs.axis = [0 0 1]

zfs.tau

Threshold on the spin polarization s_k = sqrt(1-sigma_k^2) of the pairs of corresponding orbitals (sigma_k: overlap of a spin-up and a spin-down orbital) included in the exchange term. Pairs with smaller s_k are left out. Smaller values are more accurate and slower; 1e-3 changes D by less than 0.5 MHz in defects with a few hundred atoms.

type: scalar

default: 0.001

example: zfs.tau = 1e-3