First principle calculations of solid nitrobenzene under high pressure

The dispersion corrected density functional theory (DFT-D) calculations were performed to study the structural and vibrational properties of solid nitrobenzene at ambient pressure. Assignments of the calculated vibrational modes were provided. Moreover, using the norm-conserving pseudopotential plus GGA-PBE function, the unit cell parameters, geometries and vibrational frequencies of nitrobenzene were examined under hydrostatic pressure from 0 to 10 GPa. The calculated pressure dependence of lattice parameters and volume were found to be close to the experimental results, but a distinct change in the bond lengths and bond angles was found around 7 GPa. According to the phonon calculations, the pressure-induced changes of the vibrational frequencies were also observed around 7 GPa. These calculated results all suggest a possible structural transformation in the crystalline nitrobenzene.