Compressibility of liquid nitromethane in the high-pressure regime

With potential functions including the harmonic intramolecular interaction and Lennard-Jones plus columbic intermolecular interactions, classical dynamic simulations were performed for liquid nitromethane. In the range of pressure from 1atm to 24.3 GPa and the range of temperature from 300  to 1300 K, we carried out constant pressure-temperatre (NPT) and constant volume-temperature (NVT) simulations. The thermodynamic properties of liquid nitromethane under high-pressure and at high-temperature have been investigated. For some thermodynamic functions, such as shock velocity and particle velocity, the classical MD simulation is close to experimental results. But the calculated Hugoniot pressure is too high compared to experimental results and the other simulations with different potentials. Similar to previous works, the computed shock temperature is lower than experiment. The pressure and temperature effects on the structural properties of denser liquid NM have been examined in terms of some characteristic pair radial distribution functions. Careful analysis of the pair correlation functions reveals that the short-range repulsion becomes very important at high density, and the Lennared-Jones potential is not suitable for nitromethane in the high-pressure regime.