Novel condensed-phase energetic materials consisting primarily of low-Z chemical elements release enormous amounts of energy upon decomposition to diatomic gas phase molecules with extremely strong covalent bonds. We apply first-principles based evolutionary search algorithms to design and characterize new poly-nitrogen, poly-carbonyl, poly-hydro-nitrogen materials at high pressures and varying stoichiometry as well as their synthesis pathways upon transformation of precursor materials under compression in diamond anvil cells and/or by shock waves.
Graphene and other two-dimensional materials, one- or several- atom -thick sheets of atoms, possess unique physical and chemical properties, which open up exciting avenues for both fundamental research and novel applications. Using atomic-scale simulation methods, such as density functional theory and classical MD, we investigate structural, electronic and mechanical properties of graphene, boron nitride, metal chalcogenides and other emergent 2D materials.
Interatomic potentials are at the heart of atomistic simulations of materials and their ability to describe quantitatively the fundamental physics and chemistry at the atomic scale is the key to achieving reliable and meaningful results. We develop novel environment-dependent bond-order potentials for covalently bonded materials by coarse-graining the quantum mechanical electronic structure within a chemically intuitive tight-binding framework, and then implementing environment-dependent screening of interatomic interactions, which are critically important for the physically-correct description of bond breaking and re-making.
Shock waves propagate through solids at supersonic speeds and, if powerful enough, can introduce irreversible plastic deformations and phase transformations. We study high-strain-rate materials response in large-scale molecular dynamics simulations of shock-induced plasticity and solid-liquid phase transformations in both single-crystal materials, and samples containing pre-existing point and extended defects, which are subjected to shock compressions of varying intensities.
Detonation is a shock-induced reaction wave propagating at supersonic speeds within an energetic material. We study complex detonation fronts in condensed-phase, including the development of the instabilities that result in cellular, transverse, pulsating-turbulent, and spinning detonations, using a novel moving window molecular dynamics technique. The atomic-scale description of a generic energetic material allows us to investigate the effect of basic physico-chemical properties, microstructure, and sample geometry on detonation wave dynamics and structure.