IRON AT HIGH-PRESSURE - LINEARIZED-AUGMENTED-PLANE-WAVE COMPUTATIONS IN THE GENERALIZED-GRADIENT APPROXIMATION

General potential linearized-augmented-plane-wave computations using the generalized-gradient approximation (GGA) of Perdew and Wang (PW-II) show excellent agreement with the measured equations of state of bcc and hcp phases to over 300 GPa, the bcc to hcp phase transition pressure, and the bcc magnetic moment. The results are a significant improvement over the local-spin-density approximation and the earlier PW-1 GGA functional. The bcc phase is mechanically unstable at high pressure with respect to a tetragonal strain, and is thus unlikely to exist in the earth's inner core.