Structural transformation and absorption properties of 2,4,6-Trinitro-2,4,6-triazacyclohexanone under high pressures

The structural, electronic and absorption properties of 2,4,6-Trinitro-2,4,6-triazacyclohexanone (K-RDX) under hydrostatic compression of 0–100 GPa have been studied by using density functional theory (DFT) calculations. The results show that the variation tendency of lattice constants (a, b, and c) is anisotropic, and b is much stiffer than a and c in the same pressures. The structure transformation occurs at the pressure of 70 GPa leading to two new covalent bonds C2-N5 and O4-N6. The analysis of band gap and density of states (DOS) of K-RDX indicate that it becomes more sensitivity under compression. The absorption spectra show that K-RDX have relatively high optical activity with the increasing pressures and the structure transformation is also observed at 70 GPa.