Crystal Packing and Molecular Dynamics Studies of the 5-Nitro-2,4-dihydro-3H-1,2,4-triazol-3-one Crystal

We have developed an intermolecular potential to describe the β-structure of the 5-nitro-2,4-dihydro-3 H -1,2,4-triazol-3-one (NTO) crystal in the approximation of rigid molecules. The potential is composed by pairwise Lennard-Jones, hydrogen-bonding terms and Coulombic interactions. Crystal-packing calculations performed with the proposed potential acceptably reproduce the main crystallographic features of the crystal and yield very good agreement with the estimated lattice energy. These findings are also supported by the results of isothermal−isobaric molecular dynamics (MD) simulations at zero pressure for temperatures ranging from 4.2 to 400 K. Throughout the MD simulations the average structure of the crystal maintains the same space group symmetry as the one determined experimentally. The thermal expansion coefficients calculated for the model indicate anisotropic behavior.