Title: Reliability and applicability of magnetic force linear response theory: Numerical parameters, predictability, and orbital resolution,
Abstract: We investigated the reliability and applicability of so-called magnetic force
linear response method to calculate spin-spin interaction strengths from
first-principles. We examined the dependence on the numerical parameters
including the number of basis orbitals and their cutoff radii within
non-orthogonal LCPAO (linear combination of pseudo-atomic orbitals) formalism.
It is shown that the parameter dependence and the ambiguity caused by these
choices are small enough in comparison to the other computation approach and
experiments. Further, we tried to pursue the possible extension of this
technique to a wider range of applications. We showed that magnetic force
theorem can provide the reasonable estimation especially for the case of
strongly localized moments even when the ground state configuration is unknown
or the total energy value is not accessible. The formalism is extended to carry
the orbital resolution from which the matrix form of the magnetic coupling
constant is calculated. From the applications to Fe-based superconductors
including LaFeAsO, NaFeAs, BaFe$_2$As$_2$ and FeTe, the distinctive
characteristics of orbital-resolved interactions are clearly noticed in between
single-stripe pnictides and double-stripe chalcogenides.