Spin fluctuations-corrected DFT for Fe-based superconductors

Albeit density functional theory (DFT) is, at the moment, the most appropriate tool for treating itinerant magnetism, its mean field implementations -local spin denstity approximation (LSDA) with or without gradient corrections- underestimate the effect of non local spin fluctuations. As a result DFT fails in reproducing, at the same time, the crystal structure and the amplitude of local moment in near critical systems. In this talk I will present a simple method for correcting the magnetic properties of itinerant systems in LSDA. The method is called reduced Stoner theory (RST). I will apply this method to study the ferromagnetic-paramagnetic transition under pressure in Ni$_3$Al itinerant ferromagnet and for describing the puzzling temperature behavior of the local moment found in doped-CaFe$_2$As$_2$ pnictides.