Study of elastic anisotropy for 1, 3, 5-trinitro-1, 3, 5-triazacyclohexane by supramolecular structural unit

The relation between elastic property and crystal structure provides a foundation for designing new materials with desired properties understanding the chemical decomposition explosion of energetic materials. supramolecular structural unit is proposed as smallest to quantitatively characterize anisotropy 1, 3, 5-trinitro-1, 5-triazacyclohexane (RDX). refers nearest-neighbor coordination polyhedron one molecule. RDX composed 15 molecules, analyzed by total molecular number density intermolecular interactions. modulus model established on assumption that 1) molecule sphere rigid-body; 2) interaction regarded linear spring, i.e. it described bond-spring model; 3) molecules are close-packed in series mode. based demonstrates intrinsically determined number, equilibrium distance pair, force constant, angle non-bonding normal face. constant calculated second derivative respect centroid distance. expressed summation van der Waals electrostatic interactions COMPASS (condensed-phase optimized potentials atomistic simulation studies) II forcefield. moduli 21.7, 17.1, 20.1, 19.1, 15.3 GPa (100), (010), (001), (210), (021) faces, respectively. calculation results consistent theoretical values computed functional theory. Excluding RDX(001), accord experimental measured resonant ultrasound spectroscopy (RUS), impulsive stimulated thermal scattering, Brillouin spectroscopy, nanoindentation methods. value (20.1 GPa) RDX(001) overestimates range 15.9–16.6 GPa. reason can be attributed rigid-body approximation flexible which ignored motion deformation ring NO<sub>2</sub> groups when external loads applied RDX(001). suggest mainly due