Improving the charge density normalization in Korringa–Kohn–Rostoker Green-function calculations

Abstract

The truncation of angular momentum expansions in the Korringa–Kohn–Rostoker Green-function method introduces a charge normalization error and disallows calculation of the Fermi level and the charge density in a consistent manner. It is shown how this error can be compensated by Lloyd’s formula, in particular if this formula is applied to normalize the Green function everywhere along the complex energy contour used for the integration of the charge density. The advantages of the improved normalization over the conventional one are illustrated by density-functional calculations for CrAs, the dilute magnetic semiconductor Ga1−xMnxN and a Si12Fe8 multilayer. It is shown that only the improved normalization leads to correct integer values of the magnetic moments in the half-metallic state of CrAs and Ga1−xMnxN and to a correct band alignment of Fe and Si states in the multilayer.

Ab initio electronic and magnetic properties of half-metallic NiCrSi and NiMnSi Heusler alloys: The role of defects and interfaces

“…73,74 Both methods as we will discuss later give similar results for the bulk alloys. FPLO is suitable to study the disorder within the coherent-potential approximation (CPA).…”

Exchange interactions and Curie temperatures of the tetrametal nitrides Cr4N, Mn4N, Fe4N, Co4N, and Ni4N

“…The energy integration of the Green's function was done with 40 points along an arc in the complex plane. In order to improve the total charge convergence with respect to l max , Lloyd's formula was applied for the determination of the Fermi energy [32,33]. The exchange-correlation potential was modeled within the generalized gradient approximation of Perdew, Burke, and Ernzerhof [34].…”

Band bending at the surface of Bi2Se3 studied from first principles

“…Though, the correct position of the Fermi energy is essential for insulator systems. Several previous works [38][39][40] proposed a procedure to correct the value of the Fermi energy in a self-consistent way based on the Lloyd's formula [41]. Following this procedure we obtained the proper Fermi energy by re-normalizing the wave functions in order to obtain the correct space-integrated charge distribution.…”