Role of Electronic States in Initiation

It is important to distinguish between the activation energy used here (to initiate self-sustaining reaction) and the activation energy applicable to thermal decomposition. The latter case is concerned with localized chemical processes that occur under noncooperative (no self-sustaining reaction) conditions. After a moderate amount of decomposition, the shape of the curve may change (changing also E and E ), but the system remains in a minimum near R1. 

Any explosive has a number of reaction coordinates and paths of the type indicated by the figure. The energy required to initiate explosive reaction, is different for each explosive and for each reaction path. This leads to differences in observed activation energies depending on the material, the stimulus, and the localization and time profile of energy input. Materials with small activa- 

It has been postulated that initiation could also arise from purely optical excitation of the electrons within the explosive molecules or soHd [13], and Williams [11] considered theoretically the relationship between the electronic energy states, chemical instability, and initiation  

Quantum mechanically, all information about a physical system is contained in its wavefunction The coordinate r stands for all the electronic coordi- 

Mj and from equipartition of energy, it is evident that the electrons move much more rapidly than the nuclei. Thus at each instant the motion of the electrons can be determined as though the nuclear positions or coordinates were fixed. Their motion can then be determined parametrically as a function of the nuclear coordinates since the electrons exist in separable, approximate stationary states that are smoothly modified by the motion of the nuclei. This is the adiabatic approximation of Born and Oppenheimer [14]. In accordance with this approximation, the wave function can be put into the form 

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