Determine the kinetics of electronic-entropy-driven phase transformations

Determine whether, and how rapidly, the electronic-entropy-driven phase transformations predicted for compressed iron oxides occur by quantifying the effects of nucleation, growth, interfacial energies, activation barriers, defects, and atomic rearrangements under electronic excitation.

Background

The finite-temperature density-functional-theory calculations determine phase-boundary locations from relative electronic Gibbs free energies, thereby identifying the thermodynamic driving force for transformations among compressed iron-oxide phases. However, a free-energy crossing alone does not establish that a transformation will occur on experimentally relevant timescales or reveal the pathway by which it proceeds.

The unresolved issue concerns transformation kinetics, including nucleation and growth, interfacial energies, activation barriers, defects, and the ability of the lattice to undergo the required atomic rearrangements. The paper indicates that addressing this problem will require multiscale methods combining FT-DFT free-energy landscapes with atomistic approaches such as ab initio molecular dynamics and enhanced sampling, as well as mesoscale phase-field modeling.