Structures and Equation of State of ε-Fe under High Pressure

The equation of state (EOS) and the axial ratio c/a of ε-Fe at high pressures are investigated by using the generalized gradient approximation (GGA) within the plane-wave pseudopotential density functional theory (DFT). The
results show that at the lower pressure, the EOS of ferromagnetic ε-Fe is consistent with the experimental result. While at higher pressure, the EOS of the nonmagnetic ε-Fe is in good agreement with the experimental result. Meanwhile, we find an obvious increase of the axial ratio c/a with pressure, and there is only a small increase with increasing temperature at high pressure.