Comment on "On the accuracy of force fields for predicting the physical properties of dimethylnitramine"

The use of force field based on atomic quantum chemistry (QC) to predict the physical properties such as unit cell parameters, bulk modulus, and melting temperature of crystal dimethylnitramine (DMNA), is discussed. Simulations of a DMNA crystal, which consists of 160 molecules arranged in the super cell with 4 × 4 × 5 unit cells, was performed using the force fields. The Edwald summation was used to detect long-range electrostatic interactions. A combined molecular dynamics (MD) and Monte Carlo simulation protocol was used to simulate the crystal. The apparent melting temperature for each system is determined by a brutal force heating of the crystal and monitoring the system volume and molecular mean-squared displacements (MSD). Molecualar mechanics (MM) using the force fields and QC calculations confirms agreement between DMNA conformational energies for rotation of NO2.