Dynamical stability of Fe-H in the Earth's mantle and core regions.
The core extends from the depth of 2,900 km to the center of the Earth and is composed mainly of an iron-rich alloy with nickel, with 10% of the mass comprised of lighter elements like hydrogen, but the exact composition is uncertain. We present a quantum mechanical first-principles study of the dynamical stability of FeH phases and their phonon densities of states at high pressure. Our free-energy calculations reveal a phonon-driven stabilization of dhcp FeH at low pressures, thus resolving the present contradiction between experimental observations and theoretical predictions. Calculations reveal a complex phase diagram for FeH under pressure with a dhcp --> hcp --> fcc sequence of structural transitions.
Isaev
Eyvaz I
EI
Theoretical Physics Department, Moscow State Institute of Steel and Alloys (Technological University), 4 Leninskii Prospect, Moscow 119049, Russia.
Skorodumova
Natalia V
NV
Ahuja
Rajeev
R
Vekilov
Yuri K
YK
Johansson
Börje
B