Theoretical Modeling Considerations [INACTIVE]
[CONCLUDED Year 5]
One of the main challenges in dealing with the threat of terror is the appearance of unknown improvised explosive devices (IEDs). There is a need for rapid assessment of the yield, sensitivity, and safe disposal of these explosives. In addition, procedures for detection are needed, specifically, remote detection if possible. Project R1-D.1 suggests using computational methods as a first rapid response to these threats. We have the capability to supply such data without having to synthesize the hazardous material, which is time consuming and dangerous.
Computer simulations are, in most cases, the fast lane for the evaluation of unknown improvised explosive devices (IEDs). Currently, this project employs quantum chemical (QC) calculations for the individual properties of molecules and reactive molecular dynamics (RMD) for the bulk properties of molecules. QC and RMD calculations can identify fundamental properties, such as the detonation mechanism and yield of new materials.
Experimental studies are time consuming, expensive, and potentially dangerous. The results of the theoretical research conducted by this project could be used to guide and focus experimental efforts to synthesize, characterize, and detect materials such as IEDs. For example, Project R1-D.1 has collaborated with R1 Thrust Leader, Prof. Jimmie Oxley and her colleagues to validate the mechanisms of synthesis and degradation of new explosives by combining simulations and experiments (see Projects R1-A.1, R1-B.1, and R1-C.2).
Over the past three years, this project’s primary focus has been the investigation of the properties of a wide variety of homemade explosives (HMEs) and understanding the relationship between different explosives characteristics and their sensitivity, thermal decomposition mechanism, vibrational spectroscopy, and relative stability. The first explosive studied was hexamethylene triperoxide diamine (HMTD) and its decomposition pathway in different environments both theoretically and experimentally with the goal of developing a safe disposal scheme. This project also examined the influence of nanometer size defects in erythritol tetranitrate (ETN) on its sensitivity for detonation. In addition, a joint experimental and theoretical investigation was conducted to understand the thermal decomposition mechanism of ETN together with its infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy. This study is still in progress, examining the relative stability of other nitrated homemade explosives based on sweeteners. In addition to ETN, this project studies xylitol pentanitrate, mannitol hexanitrate, and sorbitol hexanitrate.
Our immediate goal is to advance our computational methods to address the potential hazard of explosive liquid mixtures. Currently, these liquids are hard to detect and their explosive properties are difficult to predict. This project is examining two main families. The first consists of mixtures of nitromethane with different oxidizing and fuel liquids including H2O2, acetone, methanol, and ethanolamine. The second group consists of mixtures between hydrogen peroxide and different “fu” materials including urea and sugar.
The theoretical simulations are aimed at providing experimental groups with thermodynamic, kinetic, and spectroscopic data of new explosives and of modified known explosives. The primary target of the theoretical study is to provide the means to detect, destroy, and prevent the synthesis of known and new homemade explosives.Year 5 Workplan
Hebrew University, Jerusalem
Faculty and Staff Currently Involved in Project
Students Currently Involved in Project
- David Furman