How Do We Characterize and Control Matter Away - Especially Very Far Away - from Equilibrium? Progress on Grand Challenge New Horizons for Grand Challenge Remaining Challenge Refreshed Grand Challenge? The crucial role of off-stoichiometry in irradiated oxides opens a new research frontier that has not received attention in the past. The role of off-stoichiometry in cluster dynamics and in microstructure evolution at the mesoscale can take at least a decade to tackle. The local composition variations of the oxide lattices and the composition of the emerging microstructure is found to be critical. Nucleation is found to be controlled by Frenkel defects, not Schottky defects. Extended defects such as voids are found to dictate metastable distributions of point defects in the matrix near extended defects. The scope has changed in the case of irradiation response of solid materials, especially in regard to the crucial role of off-stoichiometry in defects and microstructure dynamics. The electrochemical effects associated with charged defects and the fact that stoichiometry represents the natural state of an oxide makes off-stoichiometry the most critical dynamical variable in understanding irradiation response of oxides. The current statement of the Grand Challenge is still valid. And the grand challenge should continue because the scope is both wide and important from a scientific and a technological points of view. Submitted by: Ben Larson Affiliation: Oak Ridge National Laboratory

How Do We Characterize and Control Matter Away - Especially Very Far Away - from Equilibrium? Progress on Grand Challenge New Horizons for Grand Challenge Remaining ChallengeRefreshed Grand Challenge? The broad scope of materials behavior under highly nonequilibrium conditions continues to be a Grand Challenge that will require attention for greater than decadal time scales Critical computational and experimental progress has been made on fundamental understanding of anharmonic vibrational interactions and predicting their impact on nonequilibrium flow of energy The absence of similar progress in technologically and fundamentally important strongly correlated materials suggests anharmonicity in correlated materials in particular as a New Horizon within this Challenge The overall statement of characterizing and controlling materials properties under extreme and highly nonequilibrium conditions remains both valid and critical for progress in advanced technologies Submitted by: Ben Larson Affiliation: Oak Ridge National Laboratory

Anharmonicity in Strongly Correlated Materials Important first-principles computational progress has been made on non- strongly correlated materials employing ab initio molecular dynamics in connection with the development of nonlinear and finite temperature lattice dynamics techniques as applied to explain the anomalous phonon behavior in PbTe. [Chen et al., Physical Review Letters 113, (2014); Li et al., Physical Review Letters 112, (2014)] On the other hand, inelastic neutron scattering experimental measurements of phonon spectra and phonon density of states of UO 2 as the most widely used nuclear fuel and a fundamentally important strongly correlated electron material have revealed unexpected gaps in our understanding of anharmonicity with more complex vibrational and electronic complexities. [Pang et al. Physical Review Letters 110, (2013); Pang et al. Physical Review B (2014)] Density functional theory and Dynamical Mean Field Theory approaches have so far not been successful (anharmoincity predictive wise) within the 5f UO 2 system, nor do instances of success in other strongly correlated materials seem to have been reported Submitted by: Ben Larson Affiliation: Oak Ridge National Laboratory