Shattering dissociation in high-energy molecular collisions between nitrate esters

We present ab initio molecular dynamics simulations of head-on collisions between ethyl nitrate molecules at collisional energies from 200 to 1200 kJ/mol. Above a threshold energy, an increasing fraction of the collisions led to rapid dissociation on impact--"shattering." The probability of the shattering dissociation was derived from the quasiclassical trajectories sampling the initial vibrational motion at T(vib) = 300 K. Even for the zero impact parameter and a fixed orientation considered, the observed dissociation probability exhibited a wide spread (much larger than kT(vib)) as a function of the collision energy. This is attributed to variations in the initial vibrational phase. We propose a closed-form expression for the energy-dependent dissociation probability that captures the dependence on the phase and use it to analyze the probability of the shattering dissociation of a larger nitrate ester, pentaerythritol tetranitrate.