2019/10/21 by Asako Terasawa, Munehisa Matsumoto, Taisuke Ozaki +1 · 4 citations
Physics and Astronomy · #Crystallography and Radiation Phenomena #Nuclear physics research studies #Advanced Chemical Physics Studies
paper · doi:10.7566/jpsj.88.114706
For large-scale computation of the exchange coupling constants Jij, we reconstruct the Liechtenstein formula for localized orbital representation and simplify the energy integrations by adopting the finite pole approximation of the Fermi function proposed by Ozaki [Phys. Rev. B 75, 035123 (2007)]. We calculate the exchange coupling constant J1NN of the first-nearest-neighbor sites in body-centered-cubic Fe systems of various sizes to estimate the optimal computational parameters that yield appropriate values at the lowest computational cost. It is shown that the number of poles needed for a computational accuracy of 0.05 meV is determined as ∼ 60, whereas the number of necessary Matsubara poles needed to obtain similar accuracy, which was determined in previous studies, is on the order of 1000. Finally, we show Jij as a function of atomic distance, and compared it with one derived from Korringa-Kohn-Rostoker Green's function formalism. The distance profile of Jij derived by KKR formalism agrees well with that derived by our study, and this agreement supports the reliability of our newly derived formalism.