First-principles study of structural, elastic, electronic and optical properties of RDX under pressure

The influences of pressure on structural, elastic, electronic and optical properties of α-RDX under pressure from 0 to 40 GPa have been investigated by performing first-principles calculations. The obtained structural parameters based on the GGA-PBE+G calculations are consistent with previous experimental values. The results of B/G, C₁₂-C₄₄ and Poisson's ratio show that α-RDX has changed to ductility under pressure between 0 and 5 GPa. The obvious rotation of NO₂ group in the equatorial position appears, especially in the range of pressure from 10 to 15 GPa, which influences the elastic and mechanical properties of α-RDX. Moreover, we find that the electrons of α-RDX become more active under higher pressure by comparing the curves of DOS under different pressure. Furthermore, the anisotropy of optical properties under different pressures has been shown.