Scaling relationships for nonadiabatic energy relaxation times in warm dense matter: toward understanding the equation of state.

Understanding the dynamics of electron-ion energy transfer in warm dense (WD) matter is important to the measurement of equation of state (EOS) properties and for understanding the energy balance in dynamic simulations. In this work, we present a comprehensive investigation of nonadiabatic electron relaxation and thermal excitation dynamics in aluminum under high pressure and temperature. Using quantum-classical trajectory surface hopping approaches, we examine the role of nonadiabatic couplings and electronic decoherence in electron-nuclear energy transfer in WD aluminum.

A two-temperature model of radiation damage in α-quartz.

Two-temperature models are used to represent the physics of the interaction between atoms and electrons during thermal transients such as radiation damage, laser heating, and cascade simulations. We introduce a two-temperature model applied to an insulator, α-quartz, to model heat deposition in a SiO(2) lattice. Our model of the SiO(2) electronic subsystem is based on quantum simulations of the electronic response in a SiO(2) repeat cell.

Shock compression of a fifth period element: liquid xenon to 840 GPa.

Current equation of state (EOS) models for xenon show substantial differences in the Hugoniot above 100 GPa, prompting the need for an improved understanding of xenon's behavior at extreme conditions. We performed shock compression experiments on liquid xenon to determine the Hugoniot up to 840 GPa, using these results to validate density functional theory (DFT) simulations. Despite the nearly fivefold compression, we find that the limiting Thomas-Fermi theory, exact in the high density limit, does not accurately describe the system.

Synthesis and characterization of amphiphilic phenylene ethynylene oligomers and their Langmuir-Blodgett films.

We report the synthesis of a series of amphiphilic molecular building blocks that can be self-assembled at the air-water interface to form two- and three-dimensional nanostructures with tunable optoelectronic properties. Compression of these molecular building blocks using the Langmuir-Blodgett method gives rise to monolayer and multilayer thin films with different packing densities and electronic properties that are tunable due to varying pi-pi (hydrophobic) interactions. Depending on the noncovalent interaction between chromophores, we observe a transition toward denser packing with increasing number of phenylene ethynylene repeat units.