Ab initio study of pressure-induced metal-insulator transition in cubic FeGe

Ab initio density functional calculations have been performed for cubic FeGe. The calculated equilibrium geometry as well as the ordered magnetic moment in the ground state are in excellent agreement with experiment. To study the influence under pressure, we survey the electronic structure varying the lattice constant while fully relaxing all atomic positions for magnetic and nonmagnetic states. At a critical pressure p(c) similar or equal to 40 GPa, the magnetic solution becomes unstable and the ordered magnetic moment disappears. The breakdown of magnetism is associated with the opening of a gap in the electronic density of states which highlights a pressure-induced metal-to-insulator transition. Standard exchange-correlation functionals based on the local density approximation and the generalized gradient approximation (GGA) suggest a continuous decrease in the ordered magnetic moment under pressure. This changes to first order when the nonlocal character of the exchange-interaction is accounted for, with the hybrid functional B3LYP.