Theoretical Modeling Considerations
The theoretical effort is aimed at obtaining an in-depth understanding of the characteristics of new explosive materials, with an emphasis on homemade explosives (HMEs). In addition, the theoretical studies are aimed at assisting the experimental investigations within ALERT in deciphering reaction mechanisms. The theoretical methods are based on ab-initio quantum chemical (QC) calculations and ab-initio molecular dynamics (AIMD). For simulating larger molecular ensembles, reactive molecular dynamics (RMD) methods are employed.
The main challenge is to develop predictable theoretical methods that are able to assess the performance of known and unknown explosives from first principles computational methods. Another challenge is to provide the experimental groups with thermodynamic, kinetic, and spectroscopic data of new explosives and of modified known explosives. The main sub-projects investigated at present include:
- Establishing the relation of the oxidizer-fuel ratio in liquid HMEs detonable mixtures. The system chosen is nitromethane and its mixtures include, at different ratios, water and various potential fuels such as cyclo-hexane, ethanol, etc. The main aim in these calculations is on understanding the detonability of mixtures with different compositions and its relation to variations in detonation mechanism.
- Calculating accurate equations of state for different HMEs using RMD and AIMD calculations. The outcome can be used as input in thermodynamic codes such as CHEETAH. The data obtained in these studies will allow for a reliable hydrodynamic simulation of the detonation of improvised devices based on these HMEs.
- Employing QC calculations to understand the decomposition process of HMEs in different environments (i.e. pH dependences). These types of calculations will assist in the design and assessment of additives to oxidizers (such as H2O2) that will prevent using them for the synthesis of HMEs. The QC calculations will also assist in the design of efficient routes for the destruction of HMEs.
- Studying spectroscopic characteristics of HMEs. The main aim is to assist in developing protocols for stand-off detection schemes.
- Studying the interaction between short, intense laser pulses and thin films of explosives, and understanding the basic mechanisms that lead to parent molecule ejections. The aim is to understand the mechanism that controls the process to allow optimization of detection schemes and analytical chemistry schemes based on the laser ablation process.
The theoretical investigation of such HMEs yields thermodynamic, kinetic, and spectroscopic data for HME systems and allows the evaluation of their detonation sensitivity and performance. The data obtained in these studies has never been reported and it is extremely important to understanding HMEs.Year 4 Workplan
Students Currently Involved in Project
- David Furman
- Natan Kalson
- Paz Elia
- Sharon Yarden