  Using an artificial neural-network machine learning interatomic potential, we
have performed molecular dynamics simulations to study the structure and
dynamics of Fe90Si3O7 liquid close to the Earth's liquid core conditions. The
simulation results reveal that the short-range structural order (SRO) in the
Fe90Si3O7 liquid is very strong. About 80% of the atoms are arranged in
crystalline-like SRO motifs. In particular, ~70% of Fe-centered clusters can be
classified as either hexagonal-close-pack (HCP/HCP-like) or icosahedral
(ICO/ICO-like) SRO motifs. The SRO clusters centered on Fe, Si, or O atoms are
strongly intermixed and homogenously distributed throughout the liquid. The
atomic structure of the liquid and the fractions of dominant SRO clusters are
not sensitive to pressure/temperature used in the simulations except that the
SRO of the O-centered clusters is enhanced close to inner core pressures. The O
diffusion coefficient is about 2-3 times larger than the Fe and Si ions and
increases more rapidly in the deeper core regions.
