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Explosive Processes in Molecular Systems

#0657-2


Simulation of Explosive Processes in Molecular Systems under the Action of External Factors Using Quantum Chemical and Molecular Dynamics Methods

Tech Area / Field

  • CHE-THE/Physical and Theoretical Chemistry/Chemistry

Status
3 Approved without Funding

Registration date
07.05.1998

Leading Institute
VNIITF, Russia, Chelyabinsk reg., Snezhinsk

Supporting institutes

  • Institute of Organic Chemistry, Russia, Moscow

Collaborators

  • Los-Alamos National Laboratory, USA, NM, Los-Alamos\nMolecular Simulations Inc., USA, CA, San Diego

Project summary

The main goal of the Project is to develop the theoretical model and to adapt the available programs of quantum chemistry and molecular dynamics to the investigation of explosive processes taking place in molecular systems under the action of external factors.

Some processes, which can lead to explosion, are initiated in the explosives under intensive external actions. In industry simile explosion often lead to catastrophic consequences. Work under the Project includes the study into questions concerned with processes taking place with molecules of explosives under external actions and with the determination what molecular parameters are associated with explosion initiation parameters.

Directions of Work

1. One of the directions of work (Tasks A, the static approach) is devoted to the study into the correlations of the explosive initiation parameters with the molecular structure parameters for multi-atomic explosives. The reactivity indices (RI) for aromatic and heterocyclic nitrocompounds will be calculated by using semiempirical quantum chemistry techniques in the "isolated molecule" approximation as well as within the framework of the "molecular cluster" model. On the basis of the obtained data some recommendations will be formulated with respect to constructing safe industrial explosives.

2. Second direction (Tasks B, C, D, the dynamics approach) - modeling of the ensemble evolution of small molecules of explosives (HN3 type) under external actions.

2.1. One of the proposed ways for solving the set task is based on the application of the ab initio molecular dynamics (task B). The moment of principle consists in building the model function of probability for the decay of hydrazoic acid molecules during impact. The next step: mathematical modeling of the behavior of the system consisting of ~50 molecules of the simplest explosives on the basis of the joint usage of the adapted program of the ab initio molecular dynamics and the model function of the molecules decay probability during collision.

2.2. The second methodological approach (Tasks C, D). At first the quantum-chemical calculations will be performed with respect to the potential surface of a number of the key structures containing atoms of nitrogen and hydrogen in the reaction coordinates of the most important channels of the initial compound decomposition. Then the choice of the acceptable analytical potentials of interactions will be carried out. On the basis of using the modified program of molecular dynamics and potentials obtained by the potential surface approximation, the mathematical modeling of processes taking place in the ensemble of the simplest explosive molecules (type of hydrazoic acid and nitromethane) will be performed. The comparative analysis of the obtained results with those provided by MSI's COMPASS force field technology for similar compounds will be performed.

3. Additional investigations (Tasks E), Calculations of probability for transferring the translation energy of the particle, flying against the molecular crystal surface, into the intermolecular vibrations of the crystal and the intramolecular vibrations of molecules forming the crystal depending on the photon spectrum of the crystal.

Role of Foreign Collaborators

The work under the Project will be interested for:


I. Los Alamos National Laboratory (LANL, USA);
II. Molecular Simulation Inc. (MSI, USA).

The role of foreign collaborators under the Project # 657 was discussed at the Workshops which have been held with the representatives of LANL, MSI and University of Illinois in Snezhinsk (July 1997, November 1997), Moscow (August 1997), Urbana (January 1997) and San Diego (January 1998) within the framework of PDG # 657. The key points of the cooperation with MSI within the framework of the Project # 657 have been set forth in the "Collaboration Plan".

According to arrangements achieved during the work implementation under the Project the representatives of the American collaborators will:


- get familiarized themselves the reports envisaged by the "Working Plan" of the Project and submitted by the executors with the purpose of enhancing possibility for commercialization of the computational results;
- participate in discussions of scientific progress and directions;
- formulate proposals on the directions of work with a view to improve the possibility for the commercialization of obtained results.

Such form of collaboration is traditional for the creation of MSI's Consortia. Consortia are application-focused groups of industrial researchers, leading scientists and MSI staff who develop strategy to solve problems in the areas associated with molecular modeling of different process. The modeling of processes in explosives till now has not been the area of MSI commercial interests.

Expected Results


1. More than 20 persons will be partially perted from the activity associated with the improvement of nuclear weapon.
2. Three alternative techniques will be developed for modeling at the molecular level of processes occurring in explosives under external actions by using:

- classical molecular dynamics;
- ab initio molecular dynamics;
- combined approach based upon the joint usage of classical and ab initio molecular dynamics

3. Recommendations will be given for designing molecules of safe explosives for industry on the basis of using the obtained correlation dependencies (molecular structure/explosive sensitivity).
4. On completion of the work under the Project the team of executors will form MSI's Consortium - application-focused group of researchers and MSI staff who develop strategies to solve problems associated with modeling processes in explosives at a molecular level.


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