1. Multidisciplinary Research Program of the University Research Initiative (MURI) Accurate Theoretical Predictions of the Properties of Energetic Materials Donald L. Thompson (PI) Department of Chemistry University of Missouri – Columbia

2. Motivation The need for more efficient, faster, and cheaper methods for discovering new energetic materials The Plan: ● Develop theoretical methods that can be used predict the critical properties and behaviors of notional energetic materials ● Provide theoretical guidance in the development of new energetic materials ● Better understanding of existing energetic materials ● Advances in theoretical & computational methods

3. OVERARCHING GOALS Predictive capabilities for energetic materials applicable to the chemical decomposition of condensed-phase energetic materials under extreme conditions to enhance our understanding of current materials and aid in the design and discovery of new ones. A practical method for predicting solvation and separation in supercritical fluids.

4. Specific Goals Potentials that describe the inter- and intra-molecular forces, including phase transitions and chemical reactions. Ab initio predictions of structures and properties of solids at high temperatures and pressures. Methods to predict mechanical properties and physical changes in condensed phases. Methods to predict chemical decomposition in condensed phases, particularly ignition and sensitivity in response to heating and shocking. Methods for predicting temperatures of the condensed phases and flames resulting from physical and chemical changes, including a predictive model for the “heat feedback” from the flame to burning surface. Methods for predicting solvation and separation for energetic materials in supercritical fluids.

5. Advances in basic theoretical methods Advanced methods for ab initio treatments of condensed phase materials, including chemical changes Advanced methods for ab initio predictions of reaction energetics New methods for using ab initio quantum chemistry methods in conjunction with molecular dynamics methods General universal atomic-level potentials for describing complex chemical reaction, particularly for combustion of C,N,O,H systems. Accurate methods for predicting molecular solubility Improved practical methods for computing rates Improved methods for performing atomic-level simulations Methods for realistic simulations of chemistry in condensed phases A better understanding of gas-liquid energy transfer Others…

6. Transitioning the Methods There are ongoing interactions with and feedback from the Army for the immediate transitioning of methods and results for DoD applications We are working closely with Dr. Betsy Rice to immediately hand off new developments: The models and methods are being continuously tested and incorporated into Army modeling codes.

7. The Expertise The MURI brings together the requisite expertise to develop the theory, models, computational methods, and computer codes for accurate predictions of the properties and behaviors of energetic materials.

8. The MURI Team John E. Adams (University of Missouri, Columbia) Flame-Surface Heat Exchange Herman L. Ammon (University of Maryland) Crystal Models Rodney J. Bartlett (University of Florida) Ab Initio Potential Energy Surfaces Donald W. Brenner (North Carolina State University) Reactive Potentials David M. Ceperley and Richard M. Martin (University of Illinois, Urbana-Champaign) Quantum Simulations of Materials Donald L. Thompson (University of Missouri, Columbia) Simulations and Rates Christopher J. Cramer and Donald G. Truhlar (University of Minnesota) Separation and Solvation

9. David M. Ceperley and Richard M. Martin University of Illinois, Urbana-Champaign Development of Fundamental Methods for Prediction of Properties of Materials Under Extreme Conditions  Develop methods for first-principles simulations  Provide benchmarks that can be used in constructing universal force field models

10. Rodney J. Bartlett University of Florida Ab Initio Predictions for Potential Energy Surfaces for Chemical Reactions  Develop better Q.M. methods for computing accurate PESs  Provide critical data for the classical potentials  Develop methods for direct dynamics

11. Herman L. Ammon University of Maryland Structure-Density-Heat of Formation-Sensitivity Predictions  Develop procedures for predictions of crystal structures, densities and heats of formation of energetic materials  Investigate the relationships between crystal structure/microstructure and sensitivity, compressibility, polymorphism and crystal shape  Test procedures by predictions for known energetic materials

12. Donald W. Brenner North Carolina State University Quantum-Based, Reactive Potentials for Simulating Shock Dynamics of Condensed-Phase Energetic Materials: A Bridge between Ab Initio Calculations and Experimental Shock Dynamics  Developing a transferable analytic reactive potential for C,H,O,N species, e.g., RDX & HMX, based on a bond-order formalism and ab initio data that will enable large-scale, 3-D MD simulations  Validating specific reaction paths and rates  Will predict system properties related to shock initiation and detonation for a wide range of energetic materials  Bridge molecular ab initio studies and the macroscale properties of shocked, condensed-phase energetic materials  Validation of the potentials across length scales  Initial focus: Hydrazine, RDX and HMX.

13. John E. Adams University of Missouri, Columbia Gas-Liquid Interactions: Flame-Surface Heat Exchange  Develop accurate models to aid in the prediction of the burning rate of solid-phase energetic materials  Predictions of the temperature of the fluid layer that forms between the flame and the underlying solid surface  Develop quantitative model for the energy feedback from flame to surface.  Link the MURI condensed-phase models with the steady-state continuum model of Miller and Anderson

14. Christopher J. Cramer and Donald G. Truhlar University of Minnesota Prediction of Separation and Solvation Behavior  Develop models for computing free energies of transfer of molecules between the gas phase, the liquid phase, and the solid phase, and into supercritical fluids.  Base models on both semiempirical and first-principles methods  Achieve a better understanding of the solubility and other properties of substances in supercritical fluids  Employ that understanding to develop supercritical fluid technologies for recycling and reclamation of energetic materials