Charge transference; Hybridizations; Local magnetic moments Ab initio; Antiferromagnetics; Bulk magnetization; Charge transference; Density-functional calculations; Fe atoms; Ge atom; HOMO-LUMO gaps; Hybridizations; Local magnetic moments; Magnetic behavior; Optimum geometry; Spin-polarized; Stable structures; Antiferromagnetism; Atoms; Germanium; Magnetic couplings; Magnetic moments; Magnetic properties; Magnetic materials