Rotational dynamics of nitromethane using the random phase quantum state model

Nitromethane is the smallest nitro-organic compound and a homemade explosive. In order to understand and control the explosion, we need to understand how the molecule reacts when it is ionized, sinceNitromethane is the smallest nitro-organic compound and a homemade explosive. In order to understand and control the explosion, we need to understand how the molecule reacts when it is ionized, since shock-ionization is the first step of the explosion reaction. Specifically, if we can understand how the ionization of nitro-organic compounds depends on their orientation, then we can potentially control the likelihood of ionization by controlling the orientation using laser pulses. To compute the rotational motion of nitromethane, we numerically solved the Time Dependent Schrodinger equation (TDSE), treating nitromethane as a quantum rotor interacting with a femtosecond (10-15 sec) laser pulse, which initiates rotation. We computed the rotational dynamics from temperatures around of 1 K up to 30 K. We modeled the temperature by considering a thermal distribution of initial quantum states, each of which were propagated through the TDSE code, which resulted in 5,180 initial states at 30 Kelvin, which took two weeks. We estimated that at 300 Kelvin (room temperature), the code would need to run 131,209 times to calculate the entirety of the rotational motion, which would take around a year, if we ran the code in its current form. Here we discuss the application of the "random phase wave function" method, which has been used previously for computing the rotational motion of small, asymmetric top molecules like sulfur dioxide at room temperature.