COMBINED QUANTUM-CLASSICAL THEORETICAL STUDIES OF ENERGETIC MATERIALS IN THE GAS AND CONDENSED PHASES
Abstract
There are a great many problems of interest to the Air Force that involve condensed phase systems. Important problems of this nature that will be addressed in this proposal are low melting energetic ionic liquids and deep eutectic propellants (potentially important as high energy fuels), and decomposition pathways and destabilization of aging solid propellants. To obtain a reliable understanding of these materials and processes, one must study systems with thousands of atoms over multiple length and time scales, all the while using accurate theoretical methods. High-level quantum mechanics (QM) methods can certainly provide high accuracy, but without novel theoretical approaches, QM calculations are limited to small numbers (e.g., tens to hundreds) of atoms and relatively short timescales (picoseconds). While a common approach to solving this dilemma of scale is to devise small models that can capture the essence of the actual experimental species, this approach often fails, suggesting that small model systems cannot be relied upon to represent reality. It is impossible to know a priori if and when the small model approach will work. Classical force fields (FF) are efficient and can treat thousands of atoms over much longer time scales, but they cannot readily capture certain essentials of chemistry, such as bond breaking, electronic excitation and non-adiabatic processes. Moreover, the accuracy of these classical force fields is often questionable, unless extensive benchmarking against experimental data has occurred. The research proposed herein will provide solutions to the aforementioned types of problems by developing new state-of-the-art methods that combine new approaches in quantum chemistry and classical force field-based simulations, in an integrated quantum-classical approach. The new methods range from very accurate electronic structure methods to fragmentation methods that are based on quantum mechanics (QM) and can treat very large systems, to novel classical molecular mechanics (MM) approaches that can greatly expand length and time scales. During the term of the proposed research, the newly developed quantum and classical methods will be interfaced to provide a multi-scale approach for the study of condensed phase problems of interest to the Air Force, such as ionic liquids, deep eutectic solvents and propellants, and the mechanisms by which propellants age.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 07, 2023
- Source ID
- FA95502210213
Entities
People
- Mark S. Gordon
Organizations
- Air Force Office of Scientific Research
- Iowa State University
- United States Air Force