Research On Shock Initiation Of Energetic Materials Through Efficient Simulation Algorithm

The pressure generated by explosive energetic materials can be as high as hundreds of thousands of atmospheres compound with the shock wave at the speed of several dozen kilometers per second as well as the interior at the temperature of thousands of degrees Celsius. Because the changing information of matter and energy under extreme conditions is difficult to obtain experimentally, it needs the help of computer simulation technology. Because the method of classical molecular dynamics cannot handle the chemical reaction in the case of bond breaking and restructuring and the computing cost is huge by the method of more accurate quantum dynamics calculation, most researches on reaction of energetic materials employ semi-classical molecular dynamics simulations.Because of the high efficiency of the semi-classical molecular dynamics model of DFTB, it has been widely used in the reach on cluster system and physics chemical properties of condensed matter. In order to improve the accuracy of the model of DFTB and simulate the shock wave, this thesis makes a research into the quantum molecular dynamic model of SCC-DFTB-MSST. In this model, the accuracy of electronic energy is improved by the method of self-consistent charge(SCC) and the simulation of the shock wave is calculated by the method of multiscale shock technology(MSST). Systems of RDX and water cluster are simulated through this method compared with Reax FF force field and DFTB. The results of the simulation show that the data calculated by quantum molecular dynamic model were well consistent with experimental data at high speed of shock wave. The main works of this thesis are summarized in the follows:(1) The research development, fundamental principle and related technologies of molecular dynamics and quantum molecular dynamics simulations are introduced in this thesis.(2) An efficient and relatively high precision model to simulate the physical and chemical changes of energy materials under extreme conditions is described in details. The information of electronic structure is calculated by the method of Self-Consistent-Charge Density-Functional Tight-Binding(SCC-DFTB). Taking into account the influence of shock wave, the atomic trajectory is calculated by the method of multi-scale shock technology.(3) The program to simulate the shock wave is implemented in the framework of DFTB program. Then it has been applied to the system of RDX and water cluster. The results of simulations have shown that this algorithm has higher precision compared with Reax FF and DFTB molecular dynamics simulation.