The stable phase in the core is hcp
Spin polarised calculations on all phases at core P reveal reduced _ for bcc/bct and zero _ for other phases _ no magnetism.
bcc and bct transform to fcc, orthorhombic to hcp; hcp, fcc, and dhcp remain mechanically stable at core pressures.
However, fcc and dhcp are less favourable energetically; therefore hcp is the stable phase in the core.
(harmonically at this point!)