Programme

I.1 -- Invited, VCTP-51

Date: Monday, 3 August 2026

Time: 09:20 - 10:00

Simple Theory for the Molecular Dynamics of Superionic Crystals under Extreme Conditions

Tran Dinh Cuong

Phenikaa Institute for Advanced Study, Phenikaa University

Recently, the physics community has seen a surge of interest in superionic crystals. Possessing liquid-like mobile atoms in the solid state, these materials have opened up exciting prospects in planetary science, battery technology, and nuclear engineering. However, since superionic crystals primarily exist under extreme conditions, determining their physical properties remains a huge challenge for both theorists and experimentalists. To escape this predicament, we develop a simple theory based on strong similarities between superionic solids and supercooled liquids. The elastically collective nonlinear Langevin equation is leveraged to construct the dynamic free-energy profile. The impacts of local interaction, cooperative excitation, chemical composition, isobaric heating, and isothermal squeezing on activated hopping processes are fully evaluated. Our microscopic theory can quantitatively explain how superionic crystals relax, diffuse, and deform at various pressures and temperatures. Its predictive power and computational efficiency are validated in the cases of iron (the most abundant metal in planetary cores), uranium oxide (the predominant fuel in nuclear reactors), and mixed oxide fuel (the leading candidate for plutonium disposition). These interesting results would foster more research projects on superionic crystals to actualize their enormous potential. Keywords: superionic crystals, supercooled liquids, the elastically collective nonlinear Langevin equation.

Presenter: Tran Dinh Cuong